New here; nice site. Am searching back postings. Bought a 1990 1-ton Sierra ex-telco bucket truck at auction. Per VIN, engine is 350 LO5, straight 3-speed auto trans. Has 113,000 miles. Typical GM peeled white paint. Probably part of the reason it sold at $2,100 along with the fact that exhaust manifolds are cracked and noisy. Has Onan Genset with compressor that needs some tinkering and a good Versalift 29-foot telescoping bucket set up. Also service box with lockable bins.

Mechanic friend has it now and is looking for a pair of exhaust manifolds. He'll also replace door hinge pins/bushings.

My questions are:
1. Anything to look for/worry about with this drive train?
2. It has straight 3 speed automatic. I can't yet find what model trans this is...spin off of Turbo 400?
3. Weight yesterday on scales with me in it is 9,700 pounds. Probably a bit for that 350 motor, but I'd rather have a small block than a 454 out here on flat lands.
4. Are cracked manifolds normal for these? If that suggests a problem, what?
5. What are good parts sources for 1990 GMC's??

Comments appreciated,
Dennis
WA state

 

First of all, 9700 pounds is HEAVY. My 91 454 had the same problem with the exhaust manifolds. I've actually seen that on quite a few pickups around town. Not a big deal. I think it's just age. I also agree on the 350 vs 454, but don't expect that truck to be a hotrod or to be anything faster than slow. (i doubt you expect that anyway). Transmission might be a turbo 350 or turbo 400. I never really liked 3-speeds. Rockauto.com has a lot of different parts for almost any vehicle. You could also look up lmc truck. The white and the blue paint on those years of chevy/gmc trucks always peel like crazy. They must have gotten that fixed by 1996 though.

 

You are right, I never did expect much power with the weight of this unit. That's really OK, because it will be used largely locally and we have 90% flat country here. And I don't hot rod a truck of this type anyway. I like the 350 because of maintenance costs.

I'd prefer an overdrive trans too, but again, this is OK because of above.

I'm not seeing anyone on this forum come up with unusual quirks to watch for in this model year. I guess we're all aware of the peeling paint, door hinge-pin trouble, and so-so quality cab construction.

I wish I knew what caused so much factory white paint trouble. The gray undercoat seems to stay on. Poor quality top coat? I'd like to repaint the cab, but wonder if the original trouble is the primer and would that just cause future problems with new paint on top of it again?

Dennis