1997 Chevy 2500 won't start

Is that the unit just behind the battery?

Let me revise that statement, the unit just behind the little toolbox and forward of the master cylinder. Is THAT the PCM? And BTW, what does VCM stand for?

Thanks again!

Update, we've completely disconnected the thing we think is the PCM and it's still popping fuses.

Yes

Vehicle Control Module

Substitute the fuse with a #194 bulb in a replacement socket, the bulb will glow when the short that's blowing the fuse is present, have one worker watch the state of the bulb while another goes around the truck and wiggles the wiring harnesses, when the bulb flickers or goes out, you're near the short.

The #194 bulb acts as a load in a simple series circuit because it's between V+ and the short to ground, keeps ya from letting the smoke out of the wires.

Found it! The wire to the crank position sensor had gotten up against the exhaust pipe on the passenger side of the engine and burned in two. This is a pretty unmolested truck, I'm kinda surprised this happened to it. If you have one you might want to check the wire routing and make sure it's not getting close.

Thanks again, aarcuda!