They're still in the "fish scale", but also belong to TACOM.
Last I heard, the one up hull is in CA. Littlefield bought it.
The turret is much different, along with the hull. Final drives are early M1 tank as well as the road wheels and sprockets. Track is also the same. Never saw the engine up close, but sure heard it run for days at a time. Heard it was a one up Detroit engine. Some said twelve cylinder, and even heard sixteen cylinder. Took an act of Congress to get inside that test cell!
Both XM-1 prototype tanks changed and really are different than an M1-IP. Let alone all the mechanical changes. I could tell you a lot more, but I won't.
Gary

Thanks , That's a good beginning.

There are 1:48 plans in the Hunnicutt Abrams book. Not the most detailed, but the only ones I've seen.

https://www.amazon.com/Abrams-History-American-Main-Battle/dp/1626542554/ref=sr_1_1

Has anyone seen plans for the GM XM-1 prototype that competed with Chrysler for the Abrams tank contract? Over the years I've considered scratch building one.
I've only seen a few photos, no plans. Thanks