The G62B is cosmetically identical to the G63B. It's an odd engine for a truck as it should be in a FWD car (AFAIK...) There are small differences in the FWD G6X engines like intake manifolds (radiator thermostat housing is on the opposite end compared to a RWD manifold) and external coolant gallery lay outs, but these can be swapped relatively easily. Big give away that it's out of a FWD is the engine support sticking out of the timing cover or a void in the cover where the cast iron support should be. Hey, might be wrong. The extra 200cc's will make a world of difference to your truck so finding a G63B is worth it (finding parts to rebuild it will be an easier task too) Be kind to yourself and invest in a Weber carb kit for it. The Mikuni OEM carb is unforgiving to work with if you need to rebuild or adjust it due to it's complexity. It also chokes the hell out of the engine.

*Be aware that the 4G64 EFI engines from later year model trucks will not bolt up to your transmission as it's a designated 'wide block' engine even though at first glance it looks near identical.