Warning - thread resurrection in progress! There are a few extra things to bear in mind when buying one of these trucks and it's running a Mikuni carb. The auto chokes are prone to failure. Same goes with the vacuum actuator that operates the secondary throttle shaft. If the choke refuses to open the wax pellet inside the auto choke mechanism has more than likely failed (usually easy to spot as the wax is a nasty looking thick brown gunk that has seeped all over the linkage side of the carb). If the engine is lacking power from mid range onwards there's a good chance the vacuum actuator has a split diaphragm. Both of these issues have the potential to appear on all carburetted generations of engines.

The 4G63 engine has some unusual pitfalls in the inlet manifold as the base plate under the manifold can corrode clean through and it is not a location you would normally go looking for a cooling system leak. This is as a result of debris in the cooling system making it's way into the coolant gallery in the base of the manifold and lodging there, eventually rotting it out. Also the small journal return journal from the base of the manifold to the thermostat can become blocked as this journal is very restrictive (worse case scenario - the 'choke off' point is barely wide enough to pass a pencil through). This issue kept machine shops in a steady supply of work for a while. If you are steadily losing coolant and can smell it but can't find the source, inspect the inlet manifold.