Originally Posted by cobalt327
Climb up into the engine compartment and read the casting number off of the rear of the block on the ledge behind the distributor. You will be looking for a number like "10243880" as an example, and there will also be a date code- something like "H 26 7". With that info you can determine what you have. You should see "5.7L GAS" if it's a 350, "5.0L Gas" if a 305 that could have been swapped into it. If the engine is original it will likely be a 4-bolt block.
Now, why would the fact that the engine was in a 4WD vehicle mean that YOU had to make your vehicle 4WD? The engine has the tranny bolted to it- it could care less what goes on from the bellhousing flange back, AFA 2- or 4WD.
on a side not, 4WD 88-98 (GMT-400) chevy have a sideways oil filter adapter, this should be changed out to the standard 2WD or Car one.