Jsdirt

Yep, unfortunately for me.

I didn't see one in the OP's pic - that one is definitely 21st Century, no question. EDIT: Ahh, now I see it - 2nd pic. Strange, because it's got a wiring harness up top, and the body looks '96 up. Maybe a foreign job?

That's definitely an automatic - can tell by the rounded body, and it has a pan.

It drives me nuts how this myth is spread far and wide ... YOU DO NOT NEED TO GO TO A DEALERSHIP for programming! There are plenty of mobile diagnostic guys, and competent private-name shops out there that can handle programming. Even most transmission shops do this these days. Electronics are funny like that. For the least amount of hassle, I would stick with the year and model of your truck. If you're getting a used one, make sure you get the transmission control module, and the entire wiring harness for that transmission. That way it will be plug and play - otherwise, you'll have to find and pay someone to program it. I would say you could use a different year setup, as long as you have all the above, but I'm not 100% sure on that - the electronics might not play with what is already in your BCM & PCM.

Well that explains why I didn't know wtf it was! Only Euro stuff I'm familiar with is Volvo, only because I own one.

It's definitely something this century - doesn't match up to anything in my records. Gotta be a newfangled 6, or more, speed. 6L80 maybe? You've got a transfer case there too - that should have a round tag on it with it's own ID - either New Process or Magna Powertrain built.

Thanks for the update.

Great example of how air pressure affects load carrying capacity ... and why you should never fill your tires to the MAX pressure listed on the sidewall.

Sounds like a failing HEI module, and/or pickup to me. They usually start becoming no-sparkers when they get hot, and can intermittently spark at the wrong time - sometimes off-the-charts wrong. That would definitely cause a kickback. Next time it does that, you'd have to verify that you have no spark. Even better would be watching a timing light while someone is cranking it - you'll see if the advance is getting thrown all over when it intermittently fires.

I've worked on ALOT of GMs over 30 years - never seen one of those in my life.

I don't think the engine could flex far enough to smash the starter on a square body, even with no mount material left.

Never seen a brace on any GM - doesn't mean there aren't any - just means I'm not aware of any. I think you might have the ignition timing too far advanced causing kickback - that is always deadly to starters. I've also never seen one that needed shims so big that it would bury the pinion into the ring gear, and crack the case upon tightening ... but that's something else to look for.

Could be a defective starter - sounds like the solenoid is stuck on the new starter, or it was wired in wrong. There should only be 12v on the small post of the solenoid when the key is in the crank position. If it has 12v all the time, this will happen. Another possibility is a short to power on the "crank" signal wire.

That's a classic sign of a bad connection at one of the battery terminals - I'd give all of that a good check, especially since they were just touched.

This could also be the infamous ignition switch failure. You'd have to have all your test equipment hooked up and see what is happening when it fails to crank.