Towing and rear ends

[T0ng5]

Ok so maybe a new newbie questions but I've got a few questions regarding my new to me 2004 2500HD 4x4 6.0/4l80e

 

First, looking through the manual for towing capacity and limits I noticed the models of the trucks are C-1500, C-1500, K-2500....  I though after 1999 everything was a Silverado, why are the models (in my 2004 Silverado's manual) 5 years old?  I know the C designated 2wd and K 4wd in the older models, so i'm guessing my truck is being classified as a K-2500 Crew cab short box HD?

 

Second, on that same chart it shows the engine options, and their respective limits.  The chart shows the K-2500 Crew cab short box HD 6000 V8, with only the 4.10 axle ratio. According to my RPO codes, I've got 3.73 rear gears.  Even in all the research I've done I've only found 4.10 as a option in my truck, does my RPO indicate a special ordered truck or?

 

Third, does having the towing package increase the payload or GCWR at all?

 

Really I just want to know what this truck is rated to tow

Below is my decoded RPO codes and a picture from my manual

 

Thanks for any answers you guys can provide

David

 

 

AE7	SEAT FRT SPLIT DRIVER PASS EASY ENTRY

AG1	ADJUSTER FRT ST POWER 6 WAY DRIVER SPLIT BENCH

AJ1	WINDOW TINTED DEEP ALL EXCEPT W/S AND DRS

AM7	SEAT RR FLDG

AU0	E R LOCK CONTROL ENTRY REMOTE ENTRY 970124 E E E A

AU3	LOCK CONTROL SIDE DR ELEC

A31	INDOW POWER OPERATED ALL DOORS 970310 E F E A

B30	COVERING FLOOR CARPET

B32	COVERING FRT FLOOR MATS AUX

B33	COVERING REAR FLOOR MATS AUX

B71	MOLDING WHL OPENING COLORED

B85	ORNAMENTATION EXTR MLDG BELT REVEAL

CJ3	HVAC SYSTEM AIR CONDITIONER FRT MAN TEMP CONT

CMD	PLANT CODE FLINT MI

C49	DEFOGGER RR WINDOW ELECTRIC

C6P	GVW RATING 8600 LBS/3 900KG

DF5	MIRROR I/S R/V LT SENSITIVE COMPASS O/S TEMP

DK7	CONSOLE ROOF INTERIOR CUSTOM

DL8	MIRROR O/S LH & RH REM CONT ELEC DEFOG

EVA	TEST DVT EVAP EMISSION REQUIREMENT

E63	BODY EQUIPMENT FLEETSIDE PUBX

FE9	CERTIFICATION EMISSION FEDERAL

FT2	ARM LH TORSION BAR SPRING ADJ (FT2)

FT3	ARM RH TORSION BAR SPRING ADJ (FT3)

GT4	AXLE REAR 3.73 RATIO (DUP WITH 5 X 1)

G80	AXLE POSITRACTION LIMITED SLIP

JH6	BRAKE HYD POWER 4-WHEEL DISC 9900 LBS

KC4	COOLING SYSTEM HEAVY DUTY ENGINE OIL

KNP	COOLING SYSTEM TRANS HD

KUP	THROTTLE CONTROL ELECTRONIC

K34	CRUISE CONTROL AUT0MATIC ELECTRONIC

K47	AIR CLEANER HIGH CAPACITY

K68	GENERATOR105 AMP

LQ4	ENGINE GAS 8 CYL 6.0L MFI IRON GM

MT1	TRANSMISSION 4 SPD AUTO W/ELECT CONTROLS H.D. (HYDRA-MATIC 4L80-E)

NA4	EMISSION SYSTEM GVW ABOVE 8500 LB

NP5	STEERING WHEEL LEATHER WRAPPED

NP8	TRANSFER CASE – (ACTIVE) – PUSH BUTTON CONTROL 2 SPD

NT9	EMS M EMISSION SYSTEM FEDERAL TIER 2 PHASE-OUT 211 E E E A

NZZ	SALES PACKAGE SKID PLATE "OFF ROAD" SPOT 980623 E T E A

PY0	WHL M WHEEL 16 X 6.5 ALUMINUM 890207 E 4 E A

QIW	TIRE ALL LT245/75R16/E BL R/PE ST TL OOR BL

R9Z

Unknown

SAF	LOK R LOCK SPARE TIRE HOIST SHAFT 20219 E T T A

SLM	STOCK ORDER PROCESSING CODE

TR3	GRL R GRILLE RADIATOR BODY COLOR W/CHROME EMBLEM 990303 E 0 E A

T96	FOG LAMPS - FRONT

UB0	RDO M RADIO AM/FM STEREO SEEK/SCAN. CD AUTO TONE DATA SYSTEM CLOCK ETR 3 0 8 E T E A

UK3	CONTROL STEERING WHEEL ACCESSORY 971121 E E E A

UQ3	SPEAKER SYSTEM PERFORMANCE ENHANCED AUDIO

VB3	BUMPER RR STEP CHROME IMPACT STRIP

VG3	BUMPER FRT IMPACT STRIP

VR4	TRAILER HITCH WEIGHT DISTRIBUTING PLATFORM

VXS	VEHICLE COMPLETE

V73	ANTENNA FIXED

XGK	TIRE FRONT LT245/75R16/E BW R/PE ST TL OOR 120Q

X88	CONVERSION NAME PLATE CHEVROLET

YD3	FRONT AXLE BASE EQUIPMENT FOR SCHEDULING GVW PLATE

YD6	REAR SPRING BASE EQUIPMENT

YE9	CONVENIENCE PACKAGE COMFORT & DECOR LEVEL #3

YGK	TIRE REAR LT245/75R16/E BW R/PE ST TL OOR 120Q

ZHH	SPT R TIRE SPARE LT245/75R16/E BW R/PE ST TL ALS 120Q 970626 E T E A

ZY1	COLOR COMBINATION SOLID

Z82	TRAILER PROVISIONS SPECIAL EQUIPMENT H.0.

Z85	CHASSIS PACKAGE HIGH PAYLOAD FIRM RIDE

1SB	OPTION PACKAGE 02

1SZ	DISCOUNT OPTION PACKAGE 890410 P 1 E A

6GL

Unknown

62U	CCU M PRIMARY COLOR EXTERIOR DK BLUE MET (01) 20419 E 4 E A

69D	TRIM COMBINATION CLOTH MED BEIGE (D)

69I	CCM M INTERIOR TRIM LT OAK/VERY DK PEWTER 980828 E T E A

7GL

Unknown

 

[CamGTP]

Yeah they used the C and K all the way to like 2007, atleast in all the parts store lookups I use.

 

If the RPO code in the glove box says GT4, then yeah it was a 3.73 truck.

From looking through the owners manual there is a spec in there that says the K-2500 LD truck has the option for 3.73's but it just doesn't say what the cab configuration is. If we go by that then it's 8,300lbs.

 

Most 2500's with either just say "2500" or 2500HD on the decals if they are original.

[T0ng5]

23 minutes ago, CamGTP said:

Yeah they used the C and K all the way to like 2007, atleast in all the parts store lookups I use.

 

If the RPO code in the glove box says GT4, then yeah it was a 3.73 truck.

From looking through the owners manual there is a spec in there that says the K-2500 LD truck has the option for 3.73's but it just doesn't say what the cab configuration is. If we go by that then it's 8,300lbs.

 

Most 2500's with either just say "2500" or 2500HD on the decals if they are original.

 

Thanks, I kind of guessed, but just wanted to make sure.

 

According to badging and VIN it is a HD.  Would the K-2500 table not be better indicator as to towing limit?  It looks like (according to the 8100 row) that the 3.73 gears reduce the capacity by 10%.  which would put me at 14,400#?

 

Really just trying to make sure I'm looking at this right lol

 

Edited July 26, 2021 by T0ng5

[davester]

I would say you have the K-2500 LD (4wd) truck, based on your truck not having the HVY rpo code (IDENTIFICATION/2 INCH BODY RAISE, H.D. MODEL).  Both my '04 Sierra 3500 and '06 Sierra 2500HD have that code...

 

[Formulabruce]

12 minutes ago, davester said:

I would say you have the K-2500 LD (4wd) truck, based on your truck not having the HVY rpo code (IDENTIFICATION/2 INCH BODY RAISE, H.D. MODEL).  Both my '04 Sierra 3500 and '06 Sierra 2500HD have that code...

 

And I would agree.

The 3.73 was available with a Diesel in a HD as well.

I suppose one could have ordered a 3.73 truck, but its odd to have a Towing package and HD coolers.

 I have seen some 1500HD set up like this with the semi floater rear and the non straight frame in the rear.

 Typically a 2500 has a bent style rear frame like the 1500HD( 1500 HD only available in Crew cab )

 Typically a 2500HD will have a big straight 'C" channel at the rear.

[T0ng5]

Interesting.

 

So I'm trying to understand, not argue, but

If the vin states the truck is a HD, is it not?

 

Is the HD aspect of the truck determined by one RPO code?  Because I have the Z85, Z82, and KNP which to me would imply that it is in fact a HD (in addition to the vin)

 

@Formulabruce

Not sure what you meant by "...big straight 'C" channel at the rear".  But here is the frame if that helps

 

Also my MT1 code specifies HD.

 

I swear I'm not trying to convince y'all I have the HD lol, I just want to confirm.  

I appreciate the insight guys

 

[davester]

MT1 is just that it has the 4l80e.  There isn't an LD/HD version of it.

KNP is the better cooling system for the 4l80e (external radiator for it)

z82 is probably just better trailer wiring setup (7 pin connector, or support for adding a trailer brake)

 

z85 could indicate it's HD, but between the 3.73 rear end and missing the HVY rpo, I still think it's not a "full" HD truck.

 

You might consider querying GM for the build sheet of the truck (it might show why it has a 3.73 rear end), and they might even tell you which specific entry in that list of towing specs is for your truck.  It used to be that emailing [email protected] with your name/vehicle vin they would email back the build sheet...

[T0ng5]

6 hours ago, davester said:

MT1 is just that it has the 4l80e.  There isn't an LD/HD version of it.

KNP is the better cooling system for the 4l80e (external radiator for it)

z82 is probably just better trailer wiring setup (7 pin connector, or support for adding a trailer brake)

 

z85 could indicate it's HD, but between the 3.73 rear end and missing the HVY rpo, I still think it's not a "full" HD truck.

 

You might consider querying GM for the build sheet of the truck (it might show why it has a 3.73 rear end), and they might even tell you which specific entry in that list of towing specs is for your truck.  It used to be that emailing [email protected] with your name/vehicle vin they would email back the build sheet...

Sent them a email, hopefully they respond because even if it's not a "full HD" I would imagine the towing would be higher due to the other non-HVY RPO codes, and I would like to know what this truck is capable of. 

 

Still confused as to why the Vin would say 2500HD if it's not.  We'll see

[davester]

What do you mean by "Vin would say 2500HD"?  From the VIN table in my full-service manual, it just has generic ranges for the gvwr/brake system(position 4), and the vehicle series (position 6), neither of which would explicitly tell you HD vs non-HD.

Edited July 28, 2021 by davester

[T0ng5]

@davester When I look up the VIN it says 2500 HD, I didn't realize that even a non-HD 2500 would say HD when decoded.

 

I got two build sheets, one from a local dealership and one from the email listed above.  While they both say HD, you guys where right.  Between the lack of the 2" body raise and a semi float rear end, it not a HD.  Not sure why I questioned you guys lmao. 

Lastly:

Does having the towing package increase my GCWR or my GVWR?

Does anyone know my GVWR off hand? (as a non-HD 2500)

 

From_Email.pdf From_Dealer.PDF

[davester]

It's the C6P rpo code you have above.  It should also be on the door jam sticker on the truck itself.

[T0ng5]

@davesterThe sticker is completely rubbed off.  Is that RPO defining the same gvwr that would have been on that sticker? 

[davester]

I would expect so.  My 3500 doesn't have a door sticker, but my 2500 does, and the sticker says 9200lbs, matching the c6w rpo code

[T0ng5]

Cool, thank you for your help.  I appreciate it.