GMT800 Talk, chime in

[Michaelinthetwigs]

If it wasn't for the 4 speed tranny and wind noise limitations, these gmt800s would be perfectly fine for high speed cruising. I may or may not have gotten up past 90mph this morning and she was as stable as can be.

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I got up to 120 and had some driveline vibration lolololol. Wind noise doesn't happen in mine. I usually maintain the speed limit or 10+-.. Most of the time folks pass me. Occasionally, I can't refuse hurting feelers when that lifted squatted 4x4 with loud exhaust comes by being a bully with his ebay hids and light bars plastered everywhere.. Oh what a feeling when my stock appearing truck runs off and hides from them lol... I do agree about the 4l60. A 6spd would surely help those 20+ mpg! Edited September 18, 2016 by Michaelinthetwigs

[kstruckcountry]

I like the 4 speed, honestly. With 3.73 diffs, the gears just seem to be in the right places. I do enough hilly driving I'm not sure more OD would really help me.

 

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[Daryl Z71]

I like the 4 speed, honestly. With 3.73 diffs, the gears just seem to be in the right places. I do enough hilly driving I'm not sure more OD would really help me.

 

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Wish I had 3.73's. My 3.42's suck!

[Chris]

Wish I had 3.73's. My 3.42's suck!

Add power and you will appreciate a taller gear. I can light the hell out of soft tires with 3.42 gears

[Daryl Z71]

Add power and you will appreciate a taller gear. I can light the hell out of soft tires with 3.42 gears

I'd probably be better off doing that versus changing gears.

[Michaelinthetwigs]

Well, I'd prefer adding 430 gears, keeping with factory sized or smaller tire and ALSO adding power.. LQ9 swapped but wanting headers and stall/FLT trans then cam/heads

[igotzzoom]

New knock sensors? WTF for? How do you know they're bad?

FWIW, these are what mine looked like with 163,000 on the clock. Severely rusted one was the rear one, other was front:

Edited November 19, 2016 by igotzzoom

[igotzzoom]

I like the 4 speed, honestly. With 3.73 diffs, the gears just seem to be in the right places. I do enough hilly driving I'm not sure more OD would really help me.

 

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I agree. I have 3.73s on my Avalanche, and it feels "just right." Of course, if and when I lift it and put bigger tires on it, my opinion may change, but with the stock-sized wheels and tires, the 3.73 strikes the right balance of responsive and relaxed.

Edited November 19, 2016 by igotzzoom

[Sinkhole]

I have 3.42s and the added mileage on long road trips is appreciated. I drive form Southern CT to the Poconos of PA 3 times a year and do the round trip (about 440 miles) on about 22 gallons.

Edited February 16, 2017 by Sinkhole

[Podor]

New guy here. I've been enjoying reading this post. I have owned a bunch of vehicles over the past 15 years for various reasons. My job required me to have a fairly new vehicle up until last year when they got us all company vehicles. In that timeframe, I had a '00 Suburban, '03 Silverado 1500, '11 Sierra crew cab with a Duramax and a '14 crew cab Silverado 1500, and my wife currently has a '07 Yukon XL. Now that I can have what I want, I traded my last truck in to get some cash out of it and go back to a Suburban, which was my favorite of the bunch.

 

Here are the reasons I went back to the GMT800.

1. Interior. I know there's a lot of chunky looking plastic, but the layout is my favorite. Everything is easy to reach and easy to "feel" while driving so I can keep my eyes on the road. Even though the GMT900 is supposed to be an upgraded interior, both the high end dash in my wife's and the basic dash in the '11 were pretty flimsy. The seats fit me better. It feels more roomy than my wife's '07 not just up front, but everywhere, especially in the back.

 

2. Ride and handling. The '14 was by far the best driving of the bunch, but the GMT800 have been pretty close. My wife's has quite a bit of oversteer and not much feedback. I can easily load up the front end and corner well in my '05 compared to the '07 that's a little hard to predict. I actually think my Duramax handled better than our '07 (everything is tight and aligned with new quick struts). I also like the fact that almost everything in the suspension is greasable. My '00 Suburban had all OE parts when I got rid of it with 180k miles.

 

3. Power train. I'm not a fan of the DOD and VVT. My wife's had the slugs replaced right before we bought it, so I think we're good. I will concede that the Castech head issue can be bad. The heads on the newer 5.3 are far superior performance wise too. I love the 6.2 in the newer trucks too (Maybe that's pushing me towards the GMT900). I've had two of the 6L80s and neither seemed to do too well. I had a G8 GT in the mix and it shifted horribly until I had it tuned, and it still had some issues finding the right gear and sometimes it just wouldn't shift into reverse. The '14 Silverado was worse. Not to mention, I can get a nice 4L65E for way less than the 6 speed.

 

4. Styling. I prefer the body lines to the GMT900. I couldn't catch on to the fender flair profile on either version. Totally subjective.

 

So, there you have it. Totally just my opinion. Either way, GM makes the best trucks, no matter what year!

[BOSS324]

more parts for my GMT800 2500 Suburban.

 

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[Sierra89]

Its been a while since I posted so here's an update on my 06 Sierra:

 

engine: 5.3 with 3.73 gears, (tow package)

 

I've replaced: O2 sensors, knock sensors, evap solenoid, brakes, tie rods. There's probably more but can think of it now. With only 130,000 miles its been a very reliable truck. I have some burned out lights on the radio and climate controls that bug me, but not enough to replace them yet. It has the intermediate shaft clunk, but as long as I disconnect it every 12-24 months and move it back and forth for a few minutes it goes away.

I am planning new plugs, wires, trans filter and fresh oil for transfer case/front and rear axles within the next month or so.

 

The rockers and door seams are getting rusty so I'm going to need to give them some attention as well soon.

 

My other vehicle is a 2011 Tdi which I love but VW's offer to buy it back is too good to turn down. I'm trying to justify buying another GMT-800 to replace it, but the reasonable part of me is saying I need 2 trucks like I need a hole in the head....

[TwoRiversCO]

Hello! I've been lurking around here for a long time and have learned a ton from this forum. I'm pleased to announce that my three year search for the right GMT800 finally ended this past Memorial day. It seems like the good ones go really fast around here. I thought I'd chime in with the details of my recent acquisition, and contribute what information I can to this thread along the way.

 

I ended up buying a 1999 5.3L Z71 LS, extended cab (3 door), short bed, 4:10 gears, G80, with 183,000 original miles. I don't have a picture hosting account anywhere, but the truck is in the picture associated with my account here. The previous owner purchased the truck in 2000 with 17,000 miles on it, so he'd had it a while. It's spent it's entire life in Arizona and New Mexico, and is completely RUST FREE! Fortunately, the previous owner provided me with a mountain of maintenance receipts and paperwork, which made me feel better about the purchase. He also gave me a Haynes repair manual! According to his records, the major issues he had to deal with over the years were:

 

• air conditioning;
• steering;
• ABS sensor;
• transfer case;
• transmission rebuild at 164,000.

The rest of the records are pretty standard stuff like oil changes, fluid flushes, tires, etc.

 

Problems I was aware of before buying the truck were:

• shocks all appeared to have leaked fluid;
• small oil leak (1 dime sized drop per day);
• a rubbing noise and feeling in the steering;
• a whining noise regardless of being in park, neutral, or drive;
• a metallic rattling sound around 750 RPMs (catalytic converters sound like nuts and bolts in a coffee can when I hit them with my hand);
• blown speakers in the front doors;
• dying power lock actuators.

 

The truck is in great cosmetic shape, inside and out. It's not missing any pieces, and doesn't show extensive wear. Since purchasing the truck I have:

• replaced all four shocks with Monroe Reflex Monotubes;
• replaced the upper intermediate steering shaft (Doorman part);
• drained and filled the front and rear differentials (Valvoline);
• drained and filled the transfer case (Autotrak II);
• flushed and filled the radiator (Prestone Dex-Cool);
• drained and filled the power steering fluid (Prestone);
• changed the engine oil (Castrol GTX - what the previous owner had been using);
• changed the engine and cabin air filters (WIX);
• replaced the spark plugs and ignition wires (AC Delco plugs/Delphi wires);
• replaced the PCV valve (AC Delco);
• replaced the oil pressure sending unit (AC Delco);
• installed AT tires (Kuhmo Road Ventures);
• alignment (shop said suspension components all looked good)

I'm waiting for new front door speakers to arrive from Crutchfield, and for new catalytic converters to arrive from Amazon (single assembly back to the muffler). The jury is still out on the oil leak. It was hard to pinpoint because I could see oil around the oil pan gasket and the rear main seal, but it seemed to be coming from higher up and just settling around those locations. I'm hopeful the oil pressure sending unit fixed it, but I need to get under the truck and clean it all up to be sure. I replaced the alternator thinking it was causing the whining noise, but it didn't make a difference. I'm pretty sure now that it's the power steering pump, but it still works, so I'm not sure replacing it is a top priority at this point. I believe I've noticed some improvement by refreshing the PS fluid (placebo effect maybe?). The steering issue seems better after the PS fluid and intermediate shaft, but the problem still occurs, maybe just less frequently and not quite as loud.

 

My plans for the truck are to keep it pretty much stock. My dad had one of these when I was in late high school/early college and I've wanted one ever since. I plan to use it as my daily driver (about a 5 mile commute each way), hunting, general fun with the kids, etc. From my past experience with GM trucks, and what I've read on this forum, I think it should last me quite a while so long as I keep up with it.

Edited June 9, 2017 by TwoRiversCO

[mookdoc6]

New guy here. I've been enjoying reading this post. I have owned a bunch of vehicles over the past 15 years for various reasons. My job required me to have a fairly new vehicle up until last year when they got us all company vehicles. In that timeframe, I had a '00 Suburban, '03 Silverado 1500, '11 Sierra crew cab with a Duramax and a '14 crew cab Silverado 1500, and my wife currently has a '07 Yukon XL. Now that I can have what I want, I traded my last truck in to get some cash out of it and go back to a Suburban, which was my favorite of the bunch.

 

Here are the reasons I went back to the GMT800.

1. Interior. I know there's a lot of chunky looking plastic, but the layout is my favorite. Everything is easy to reach and easy to "feel" while driving so I can keep my eyes on the road. Even though the GMT900 is supposed to be an upgraded interior, both the high end dash in my wife's and the basic dash in the '11 were pretty flimsy. The seats fit me better. It feels more roomy than my wife's '07 not just up front, but everywhere, especially in the back.

 

 

2. Ride and handling. The '14 was by far the best driving of the bunch, but the GMT800 have been pretty close. My wife's has quite a bit of oversteer and not much feedback. I can easily load up the front end and corner well in my '05 compared to the '07 that's a little hard to predict. I actually think my Duramax handled better than our '07 (everything is tight and aligned with new quick struts). I also like the fact that almost everything in the suspension is greasable. My '00 Suburban had all OE parts when I got rid of it with 180k miles.

 

3. Power train. I'm not a fan of the DOD and VVT. My wife's had the slugs replaced right before we bought it, so I think we're good. I will concede that the Castech head issue can be bad. The heads on the newer 5.3 are far superior performance wise too. I love the 6.2 in the newer trucks too (Maybe that's pushing me towards the GMT900). I've had two of the 6L80s and neither seemed to do too well. I had a G8 GT in the mix and it shifted horribly until I had it tuned, and it still had some issues finding the right gear and sometimes it just wouldn't shift into reverse. The '14 Silverado was worse. Not to mention, I can get a nice 4L65E for way less than the 6 speed.

 

4. Styling. I prefer the body lines to the GMT900. I couldn't catch on to the fender flair profile on either version. Totally subjective.

 

So, there you have it. Totally just my opinion. Either way, GM makes the best trucks, no matter what year!

 

 

Do conquer! I miss driving 800's loved em! 900's nope not at all....And as for my K2 not sure yet to early!

Edited June 9, 2017 by mookdoc6

[mandrax6001]

Any ideas what to look out for? I have an 05 GMC Sierra SLE, extended cab. Z71 off road. The engine is being rebuilt under warranty because I purchased the truck at a small dealer. Any ideas?

 

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