What makes a HD?

[Bgdsub72]

I just ran my RPO codes and my truck (04 2500) came back as having

 

JH6 - 4 wheel power disc brakes, HD

KNP - HD aux trans. cooling sys

Z85 - Heavy Duty Suspension

Z82 - HD trailering equipment

 

It almost seems as if my truck is just shy of becoming a HD, What do HD's have that I do not except for a larger bumper cover? I already found out the hard way that a regular 2500 lift kit does not fit my truck but the 2500HD lift kit was a perfect fit...

[builderpaul]

2500HD has bigger frame (notice how body seems to sit higher) and a full floating rear end. Many posts on this.

[major]

I think a 2500 HD would have a 9200# GVW and a non HD would be 8600# GVW. Plus we have that little emblem that says "HD".

[Jacqson]

I just ran my RPO codes and my truck (04 2500) came back as having

 

JH6 - 4 wheel power disc brakes, HD

KNP - HD aux trans. cooling sys

Z85 - Heavy Duty Suspension

Z82 - HD trailering equipment

 

It almost seems as if my truck is just shy of becoming a HD,  What do HD's have that I do not except for a larger bumper cover?  I already found out the hard way that a regular 2500 lift kit does not fit my truck but the 2500HD lift kit was a perfect fit...

 

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I have been researching this for awhile and here is what I found out so far between the 2500 series,1500HD & Suburban 2500(8600GVW) and the HD(9200GVW). The reason for the larger bumper is HDs have a larger Rad support to handle the Duramax so the front is actually about 2' taller than a regular 2500,1500HD. All GM 2500,2500HD and 3500 series trucks have two piece frames,the rear frames are pretty much generic to all the trucks, but the front of the frame is different depending on engine choice.The only series that you can order the duramax is the 2500HD or the 3500(9900GVW).The front suspension components are all the same except for the torsion bar loads.

Now I know bgdsub72 had problems with the lift kit on his because the spindles he had were the large ones and the ones he got were the smaller ones. I went to the local GM Truck dealer and checked about 30 2500 series non HD trucks and they all had the HD spindles, Ball joints,tie rods etc. I went into the parts department and checked the part numbers for the front end components for the HD and the 2500 series and they are all the same.The only different numbers was the rear torsion bar support bracket. The HD and 3500 had a different number than the 2500series .As far as rear axles they are all 14 bolt GM in the rear,with having thicker spring packs and torsion bar loads to compensate for different GVWs. It's almost like the HD was made for the Duramax because only the HD and the 3500 have the diesel option. Anyway if you guys find out something different than me please let me know and bdgsub72 I wonder if your truck was not made in the US and maybe that is why you had a lighter front end because all the trucks I checked were made in the US. One more thing,don't be decieved by the RPO codes because KNP and Z82 are common numbers used on other trucks as well. I will keep working on this as now I am on a mission and let me know if you guys find any discrepancies in my findings. Thanx

[major]

Wow Jacqson, you deserve some kind of award or something.

[Bgdsub72]

[ bdgsub72 I wonder if your truck was not made in the US and maybe that is why you had a lighter front end because all the trucks I checked were made in the US.

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Final assembly was Flint, MI I believe... and delivered straight to Courtesy Chevrolet in Thousand Oaks, CA...It's a US truck with a 8600GVW

 

Thats some good research there...now I wonder why the lift companys make a regular 2500 lift when all of these new 2500's use HD parts?!?! Those bastards caused me a huge headache, you can imagine how pissed I was when I had my new truck in pieces when tring to install some new spindles and they did not fit

[Jacqson]

[ bdgsub72 I wonder if your truck was not made in the US and maybe that is why you had a lighter front end because all the trucks I checked were made in the US.

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Final assembly was Flint, MI I believe... and delivered straight to Courtesy Chevrolet in Thousand Oaks, CA...It's a US truck with a 8600GVW

 

Thats some good research there...now I wonder why the lift companys make a regular 2500 lift when all of these new 2500's use HD parts?!?! Those bastards caused me a huge headache, you can imagine how pissed I was when I had my new truck in pieces when tring to install some new spindles and they did not fit

 

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I am planning on calling RCD on Monday and asking them about the HD and 2500 lift kits. When I ordered my RCD kit for my 2500 Sub it came with the right size spindles so I am going to ask them about your situation and see if they have encountered any problems like yours.I also plan on finding out why the HD rear torsion bar support is different than the regular 2500. I can imagine how you felt with your Truck all apart and the spindles you got with the kit didn't fit. Anyway have a good new years weekend and I will repost my findings for you on Monday.

[ktmjim215]

PM or Email me the first 3 and last 8 of your VIN # and I'll check GM's build info for you Monday. Include a fax # and I'll send you some info.

[vhato]

I always wondered this also.

 

So we agree the 2500LD and HD series are almost the same truck, but with a different frame and a few other MINOR things.

 

Lets go deeper. I know the 2500HD and 3500 have the 14-Bolt, Full-Floating, 10.50" Ring Gear rear axle when combined with the Vortec 6000 Engine. I also learned the 2500HD and 3500 trucks come with the 14-Bolt, Full-Floating, 11.50" Ring Gear rear axle when the Duramax or Vortec 8100 Engines are selected.

 

Now GM did/does have a 14-Bolt, Semi-Floating, 9.5" Ring Gear Rear Axle available at one time or another in both 6-lug and 8-lug configurations. I do not know if they still use it.

 

Which of the two 14-bolt Rear Axles (Full-Floating 11.50" isn't available for these trucks) does the 2500LD utilize? How about the 1500HD?

 

1. 9.5" Ring Gear

2. 10.50" Ring Gear

[Jacqson]

I always wondered this also.

 

So we agree the 2500LD and HD series are almost the same truck, but with a different frame and a few other MINOR things.

 

Lets go deeper.  I know the 2500HD and 3500 have the 14-Bolt, Semi-Floating, 10.50" Ring Gear rear axle when combined with the Vortec 6000 Engine.  I also learned the 2500HD and 3500 trucks come with the 14-Bolt, Full-Floating, 11.50" Ring Gear rear axle when the Duramax or Vortec 8100 Engines are selected.

 

Now GM did/does have a 14-Bolt, Semi-Floating, 9.5" Ring Gear Rear Axle available at one time or another in both 6-lug and 8-lug configurations.  I do not know if they still use it.

 

Which of the two 14-bolt, Semi-Floating Rear Axles (Full-Floating 11.50" isn't available for these trucks) does the 2500LD utilize? How about the 1500HD?

 

1. 9.5" Ring Gear

2. 10.50" Ring Gear

 

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For the record all the 2500 series trucks I am speaking of have an 8600GVW and 8 lug wheels).From what I saw down at the dealer the 2500(8600GVW) and the 2500HD and 3500 SRW all shared the same rear axle. All these trucks had 8 lug wheels. From what I know of Full floating axles there is a large hub that sticks out from the rear axle.Non of these trucks had this feature, now my understanding is that if the 3500 comes with dual rear wheels then it may have the full floater. I also checked gear ratios on these rear axles and the GM part number for the corresponding axle ratio is the same for all three trucks(2500,HD and 3500)SRW. Also the rear part of the frame in these trucks are all pretty much the same. I am checking into why the HD has a different rear torsion bar support. You are also correct in the fact that all these axles are semi floaters. As far as GVW goes the HD has a 9200GVW as opposed to the 2500 with 8600GVW. Now if you take a 2500 with a 6.0 and an 8600GVW and compare it to an HD with a 9200GVW you get a 600lb difference in gross vehicle weight. But if you have an HD with the Duramax and Allison you are probably adding an extra 300 lbs in weight so your actual GVW difference is about 300lbs. I will double check my findings on the rear axles as maybe they share the same housings but they may have different size ring gears as you stated.The 2500(8600GVW) has a 9.5in ring gear,I know this because when I ordered the e-locker for my truck I was told by eaton that this is the same unit that is used in the HD. Eaton makes all the lockers for the rear of NBS trucks that have the G80 option, however I am not sure about the OBS trucks. Anyway I think I have gas bagged long enough so I plan on getting a little more research done on Monday. A friend of mine is one of the Head engineers at Engine Brand Management at the Duramax facility back east,and I will give him a call on monday as well. I think between all of us we will get this thing figured out no matter how hard the General tries to hide it.

[builderpaul]

I always wondered this also.

 

So we agree the 2500LD and HD series are almost the same truck, but with a different frame and a few other MINOR things.

 

Lets go deeper.  I know the 2500HD and 3500 have the 14-Bolt, Semi-Floating, 10.50" Ring Gear rear axle when combined with the Vortec 6000 Engine.  I also learned the 2500HD and 3500 trucks come with the 14-Bolt, Full-Floating, 11.50" Ring Gear rear axle when the Duramax or Vortec 8100 Engines are selected.

 

Now GM did/does have a 14-Bolt, Semi-Floating, 9.5" Ring Gear Rear Axle available at one time or another in both 6-lug and 8-lug configurations.  I do not know if they still use it.

 

Which of the two 14-bolt, Semi-Floating Rear Axles (Full-Floating 11.50" isn't available for these trucks) does the 2500LD utilize? How about the 1500HD?

 

1. 9.5" Ring Gear

2. 10.50" Ring Gear

 

<{POST_SNAPBACK}>

 

 

 

For the record all the 2500 series trucks I am speaking of have an 8600GVW and 8 lug wheels).From what I saw down at the dealer the 2500(8600GVW) and the 2500HD and 3500 SRW all shared the same rear axle. All these trucks had 8 lug wheels. From what I know of Full floating axles there is a large hub that sticks out from the rear axle.Non of these trucks had this feature, now my understanding is that if the 3500 comes with dual rear wheels then it may have the full floater. I also checked gear ratios on these rear axles and the GM part number for the corresponding axle ratio is the same for all three trucks(2500,HD and 3500)SRW. Also the rear part of the frame in these trucks are all pretty much the same. I am checking into why the HD has a different rear torsion bar support. You are also correct in the fact that all these axles are semi floaters. As far as GVW goes the HD has a 9200GVW as opposed to the 2500 with 8600GVW. Now if you take a 2500 with a 6.0 and an 8600GVW and compare it to an HD with a 9200GVW you get a 600lb difference in gross vehicle weight. But if you have an HD with the Duramax and Allison you are probably adding an extra 300 lbs in weight so your actual GVW difference is about 300lbs. I will double check my findings on the rear axles as maybe they share the same housings but they may have different size ring gears as you stated.The 2500(8600GVW) has a 9.5in ring gear,I know this because when I ordered the e-locker for my truck I was told by eaton that this is the same unit that is used in the HD. Eaton makes all the lockers for the rear of NBS trucks that have the G80 option, however I am not sure about the OBS trucks. Anyway I think I have gas bagged long enough so I plan on getting a little more research done on Monday. A friend of mine is one of the Head engineers at Engine Brand Management at the Duramax facility back east,and I will give him a call on monday as well. I think between all of us we will get this thing figured out no matter how hard the General tries to hide it.

 

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You do know you have to remove the plastic wheel/hub cover to see the full floating hub? I have a 2500HD 6.0l and have the full floater. I don't know if the reg 2500 has this or not I suspect not. The rear axle rating on the HD is 6900lbs the 2500 only 6000.

I thought elockers where electric activated. The G80 is not electric. It is made by Eaton for both obs and nbs.

[Jacqson]

I always wondered this also.

 

So we agree the 2500LD and HD series are almost the same truck, but with a different frame and a few other MINOR things.

 

Lets go deeper.  I know the 2500HD and 3500 have the 14-Bolt, Semi-Floating, 10.50" Ring Gear rear axle when combined with the Vortec 6000 Engine.  I also learned the 2500HD and 3500 trucks come with the 14-Bolt, Full-Floating, 11.50" Ring Gear rear axle when the Duramax or Vortec 8100 Engines are selected.

 

Now GM did/does have a 14-Bolt, Semi-Floating, 9.5" Ring Gear Rear Axle available at one time or another in both 6-lug and 8-lug configurations.  I do not know if they still use it.

 

Which of the two 14-bolt, Semi-Floating Rear Axles (Full-Floating 11.50" isn't available for these trucks) does the 2500LD utilize? How about the 1500HD?

 

1. 9.5" Ring Gear

2. 10.50" Ring Gear

 

<{POST_SNAPBACK}>

 

 

 

For the record all the 2500 series trucks I am speaking of have an 8600GVW and 8 lug wheels).From what I saw down at the dealer the 2500(8600GVW) and the 2500HD and 3500 SRW all shared the same rear axle. All these trucks had 8 lug wheels. From what I know of Full floating axles there is a large hub that sticks out from the rear axle.Non of these trucks had this feature, now my understanding is that if the 3500 comes with dual rear wheels then it may have the full floater. I also checked gear ratios on these rear axles and the GM part number for the corresponding axle ratio is the same for all three trucks(2500,HD and 3500)SRW. Also the rear part of the frame in these trucks are all pretty much the same. I am checking into why the HD has a different rear torsion bar support. You are also correct in the fact that all these axles are semi floaters. As far as GVW goes the HD has a 9200GVW as opposed to the 2500 with 8600GVW. Now if you take a 2500 with a 6.0 and an 8600GVW and compare it to an HD with a 9200GVW you get a 600lb difference in gross vehicle weight. But if you have an HD with the Duramax and Allison you are probably adding an extra 300 lbs in weight so your actual GVW difference is about 300lbs. I will double check my findings on the rear axles as maybe they share the same housings but they may have different size ring gears as you stated.The 2500(8600GVW) has a 9.5in ring gear,I know this because when I ordered the e-locker for my truck I was told by eaton that this is the same unit that is used in the HD. Eaton makes all the lockers for the rear of NBS trucks that have the G80 option, however I am not sure about the OBS trucks. Anyway I think I have gas bagged long enough so I plan on getting a little more research done on Monday. A friend of mine is one of the Head engineers at Engine Brand Management at the Duramax facility back east,and I will give him a call on monday as well. I think between all of us we will get this thing figured out no matter how hard the General tries to hide it.

 

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You do know you have to remove the plastic wheel/hub cover to see the full floating hub? I have a 2500HD 6.0l and have the full floater. I don't know if the reg 2500 has this or not I suspect not. The rear axle rating on the HD is 6900lbs the 2500 only 6000.

I thought elockers where electric activated. The G80 is not electric. It is made by Eaton for both obs and nbs.

 

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Yes, I know E-lockers are electrically activated and I also know that the G80 is not electric but what I was trying to say was that I was told that the E-locker listed for my truck was the same one that is listed for the HD and I would tend to believe them as they also make the lockers for the G80 option so they would know what these lockers will fit in which axle. I was also told that the GM part numbers for the corresponding axle ratios were the same for both trucks,which would lead me to believe the difference is in the spring pack and not in the axle. I will double check on Monday. Also I do know that the Plastic wheel cover would cover the protruding Hub. Nothing I said was written in stone and I only reported what I had seen or was told by the parts guys,so bear with me as I am open to everyone elses findings as well. It will be alot easier to figure this thing out if we ask questions and pool our resources.

[vhato]

Great thread guys:

 

I have been doing more research also:

 

2500LD = 14-Bolt, Semi-Floating 9.5" Ring Gear

1500HD = Both 14-Bolt 9.5" SF and 10.5" FF Axles depending on package

2500HD/3500 = 14-Bolt, 10.5" FF

D-Max/8.1 = 14-Bolt, 11.5" FF

 

I would still like to know about the rear T-bar member being different. That intrigues me.

[Jacqson]

Great thread guys:

 

I have been doing more research also:

 

2500LD = 14-Bolt, Semi-Floating 9.5" Ring Gear

1500HD = Both 14-Bolt 9.5" SF and 10.5" FF Axles depending on package

2500HD/3500 = 14-Bolt, 10.5" FF

D-Max/8.1 = 14-Bolt, 11.5" FF

 

I would still like to know about the rear T-bar member being different.  That intrigues me.

 

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That's Great, It seems that my findings are a bit different but I will double check. Maybe the guys that are telling me this stuff are wrong or I'm not looking in the right place.I will post my T-Bar findings on monday after I check a few things out. I've been going down to that Dealer so often their going to start thinking I'm planning a robbery. LOL, I should maybe go down to another dealer just to spread it around.

[BrianH323]

What's a full floating rear?

 

Brian