The engine is in the back left corner. It is an M75, basically a militarized Chrysler 361 that was common in trucks back then, and the same engine as the early M113s. The engine is mounted "backwards", as in the fan is at the rear, the transmission is forward of the motor, then the transfer case is ahead of that. That pagoda looking thing on the roof behind the turret is the cover for the radiator intake, the radiator being suspended at an angle above the engine. The exhaust goes out the scoop that protrudes from the upper rear of the hull. The hatch in the side behind the back left wheel gives access to the batteries and air cleaner and one side of the engine. The panels inside the hull come off for service. I will post more pics when I get home, I'm at work again now. It will make sense when you see them.
Cheers
Edit: Okay, I do have one of the engine bay on the work computer...
Edit 2: and another one from the internet, nicked from armyjeep.net website
Edit 3: I notice that picture captions didn't make the trip from old site to new. To clarify orientation, both pics were taken through the right side door and looking to the rear, the left one has all the panels off, all are in place in the right pic.
Note also that the slave point is inside the hull, visible in pic 2.