[someotherguy]

The 5.7 would almost surely be 4 bolt main, as 1 tons tended to get as well.  I'd figure like most heavy duty engines it was probably slightly down on compression, given up in sake of longevity under heavy use.  At any rate, the SAE paper specs the 5.7 as 190 HP @ 4,000 RPM / 300lb-ft @ 2,400 RPM...and the 7.4 as 230 HP @ 3,600 RPM / 385lb-ft @ 1,600 RPM.

Richard

[454-3500-hd]

385 ft lbs @ 1600rpm. Good ol big block. I wonder why they st op offering them with rockwells, maybe the cost? I know the rockwells were not cheap and commanly used in military orders, at least that's what I've been told from my truck rear mechanic who is also the shop owner, he claims that he had military service contracts. Also from a retired gm engineer, who's brain is hard to pick but he let's up on some info from time to time.

I would say to let Richard suggest how to set up the child board, he is the brains of this operation! We should keep posting in this topic for a while, then after we have gather as much info as possible (Richard your doing a good job) then incorporate it, such as have the first topic in that child board a "intro" a common explanation the 3500HD . Then the next topic could be the year 1991 we could list all the specs about the 91 HD. Then 1992 and so on, we could list the changes gm made to the HD. How does that sound?

Eric

[someotherguy]

The change from Rockwell to Dana was probably a simple economics issue; they already had a partnership with Dana for many other items - it may be that the model 80 didn't exist in time for first production but they were able to bring it to market soon afterwards.  That's really a guess, though.  It seems they rushed to production on 3500HD's for 1991 after the success of the all-new 1990 1 ton cab & chassis models, and tried to use as many common components as they could as they were already proven - only upgrading or coming up with new pieces as needed to meet/exceed the design goals.

Richard

[454-3500-hd]

That makes perfect sense. was the 6.5 td the only desiel they offered in the 3500HD?

[GM Guy]

I figured I might chime in on this. the 6.5L HDs never did get the bumper with the nostrils. the reason for the nostrils it to get more air to the radiator. the filler panel does just this on the HDs, so no need for nostril bumpers.

also, the only difference I can find is the 350s in the HDs got a 6 qt oil pan, rather than the 5 qt. I believe the 454s also got a bigger pan.

[someotherguy]

My 1994 3500HD had the bumper with the holes, but being that bumpers get banged up from time to time, it could just have easily been taken from a different truck.



In fact, thinking about it, I can't imagine that the HD would have ever come with a bumper that had the Silverado trim level rub strip attached.  The bumper guards are almost uniquely a Suburban item (though I have seen them on other trucks) so that bumper is likely off a diesel 'Burb.

By the way those diesel bumpers have plastic ducting that accompanies them, though there's no way I could see it adaptable to an HD because of the difference in frame design - that big plate crossmember up front would be in the way.

Richard

[boat2fast]

I have a 1992 base model 3500HD with the following VIN 1GDKC34K7NJ503034
The truck was a municipal trade-in at a local dealer. It had almost 7,000 miles. Now it has over 13,000.
Truck specs:
350 5.7L, 5spd NV4500, Rockwell Rear. No air, no radio, manual windows and locks.
Has power steering and hydroboost brakes. Truck is equipped with a 12ft Rugby dumping rack body.
Recently I converted the truck to super single rear wheels and 285-70R19.5 Michelin rears and new Michelin 225-70R19.5 fronts.
In my state anyone with dual rear wheels and a twin axle trailer is ticket bait. Single rear wheels takes the truck off the DOT radar.
I recommend the conversion. Total rear tire capacity dropped from 15,000lbs to 13,220lbs which I could live with.
Now the truck feels like a big pick-up. It's smooth, quiet, and fun to drive.
I would like to find information on the Rockwell rear axle. It would be a worthy upgrade to install a locker.

[jd8420]

That is a Rockwell C103. There was a Detroit Locker made for it but it hasn't been available in several years.

[someotherguy]

I have a 1992 base model 3500HD with the following VIN 1GDKC34K7NJ503034
The truck was a municipal trade-in at a local dealer. It had almost 7,000 miles. Now it has over 13,000.
Truck specs:
350 5.7L, 5spd NV4500, Rockwell Rear. No air, no radio, manual windows and locks.
Has power steering and hydroboost brakes. Truck is equipped with a 12ft Rugby dumping rack body.
Recently I converted the truck to super single rear wheels and 285-70R19.5 Michelin rears and new Michelin 225-70R19.5 fronts.
In my state anyone with dual rear wheels and a twin axle trailer is ticket bait. Single rear wheels takes the truck off the DOT radar.
I recommend the conversion. Total rear tire capacity dropped from 15,000lbs to 13,220lbs which I could live with.
Now the truck feels like a big pick-up. It's smooth, quiet, and fun to drive.
I would like to find information on the Rockwell rear axle. It would be a worthy upgrade to install a locker.

Thanks for posting those details!  I think the original 5.7-equipped HD's are pretty rare.  I wonder if the purchase was a cost-saving measure since it was a city vehicle?

One thing that always surprised me were the HD's around here that were AT&T trucks.  All the ones I saw were not A/C-equipped.  That's pretty brutal when you expect your work crew guys to run around in SouthEast Texas in trucks with no A/C, but I bet it saved AT&T a lot of money on the front end.

Richard

[someotherguy]

In the spirit of posting VIN's with decoded information here are the three 3500HD's I've owned in the past:

1993 Chevrolet 3500HD 1GBKC34F3PJ108864
SPID label was illegible.  VIN decodes to USA built, Chevrolet (incomplete vehicle), 14001-16000 lb GVWR, 2WD, 1 ton, 2 dr reg cab, 6.5 td, 1993 year model, Janesville WI plant.  Appears to be original 159.5" wheelbase and no frame stiffener plates, came to me with a utility bed on it, ex-Waste Management Corp. service truck.  Never ran the VIN to get the RPO codes as it was just a parts truck.  Plain Jane manual locks, manual windows, non-tilt steering.  Originally white but repainted yellow with orange stripe likely by Waste Management.  Had very dark gray interior trim, darker than the regular light truck trim, more like the early 1988-1989 different interior colors.  Automatic trans (4L80E) and A/C-equipped.  In this picture it appears the grille and grille filler have been replaced with 1994-up pieces possibly after a crash.


1994 Chevrolet 3500HD 1GBKC34F1RJ112673
SPID label was illegible.  VIN decodes to USA built, Chevrolet (incomplete vehicle), 14001-16000 lb GVWR, 2WD, 1 ton, 2 dr reg cab, 6.5 td, 1994 year model, Janesville WI plant.  Appears to be original 135.5" wheelbase and no frame stiffener plates, came to me with no bed, title indicates former flatbed, belonged to a construction company.  Plain Jane manual locks, manual windows, non-tilt steering.  I ran the VIN to get the RPO codes, it actually came from factory in tan color (code 61U) as opposed to so many coming just plain white.  Tan interior plastics and cloth seat as well.  Manual trans (NV4500) and A/C-equipped.  Had an aftermarket cruise control module added.  Most of you here are familiar with this truck as the one I rebuilt and converted to a Vortec 7.4 and full new interior swap and eventually built it into a wrecker.  In this picture "diesel" bumper appears to not be original equipment as we discussed earlier in this thread.


1995 Chevrolet 3500HD 1GBKC34N6SJ109913
I do have a pic of the SPID label but never bothered to decode it.  VIN decodes to USA built, Chevrolet (incomplete vehicle), 14001-16000 lb GVWR, 2WD, 1 ton, 2 dr reg cab, 7.4, 1995 year model, Janesville WI plant.  Appears to be original 159.5" wheelbase and factory frame stiffener plates, came to me with no bed, formerly was a wrecker.  Power locks, power windows, tilt steering; Silverado style trim including chrome grille and composite headlights, but vinyl floormat.  It actually came from factory in gray metallic color (code 8798) as opposed to so many coming just plain white.  Gray interior plastics and cloth bench seat as well.  Manual trans (NV4500) and A/C-equipped.  Some of you may recall this is the truck I repaired the crash damage on and did a few other repairs/upgrades before selling it.


Richard