1988 3/4 Ton Chevy...Where do I start??
 

Picked up this chev a few days ago. 126,000km, 5.7l, 350V8. It runs very well but doesnt have as much grunt as I expected a 350 to have especially with these low km's. Do you guys know of any good upgrades to throw at this thing? I'll have some pictures on here in a day or so.

What are you wanting it to do ? An engine can do whatever you want if your pockets are deep enough.

How about some specs, first?
What size and kind of rear, what trans? Which 350?

Usually 3/4 ton trucks are geared to work, not run fast or get good mpg.

That's the thing, I don't know which kind of 350 it is, how can I tell? I don't want the truck to have massive power, but a fair increase from what its at now couldn't hurt. Maybe cold air intake and dials? Bigger carb?

It's a 2wd if that helps determine what kind of 350 it has

It's most likely a TBI motor, basically a computer controlled carb. Something simple would be headers and high flow catalytic converters with a decent muffler. The more an engine can breathe, the better it will perform. The other thing to realize it that as a 3/4 ton, it's designed mote for payload and towing. If it was used hard, it might be a bit tired even with relatively low miles. They also make intakes for that motor which again will help it breathe. Make a call to Jegs performance and talk to one of the tech guys, they can give you ideas on power combo's that fit your price range.

Good luck and welcome to the forums........... Rob

Here are a few pics, a little rust above rear wheel wells

its the 5.7l v8 350
it is a tbi which means throttle body injection for the fuel delivery type
as far as fuel pressure goes it should run at about 9-13psi
your fuel tank is most likely the 25 gallon tank
yoru rear end gears are most likley 3.42 or lower
if its 4wd its got 3.42
so you need to be more specific on your questions
5.7ls can put out alot of power stock but with alot of money you can build them to have about 500- 600 horse and 400-500 ft lbs of torque

How can I determine what kind of trans/diff I have?

Try here.

You can usually start by counting the number of bolts holding the back cover on. 10, 12, or 14 bolts, and go from there.
For a while, Gm was adding a small metal tag to one of those bolts that was stamped with the axle ratio. Unfortunately they weren't consistent with that, and many of those tags got discarded over the years by people servicing the rear axles, and either didn't know, or care what those little tags were. There should also be a code in the RPO list identifying the axle.

You can also google GM rear axle ID.