Yes it was indeed, the unibody was popping apart in various places like the outriggers below the doors. AMC was not well known for the strength of their bodies per se. I had troubles with the unibody coming apart at the wheel wells on the AMXes from body flexing. Of course the cars were biting hard enough to pull the wheels, in fact it was a huge problem, much work going toward making the car go forward rather than up in the air.
WE knew the value of collectible AMC cars at the time but it wasn't common knowledge back then, most did not value the cars highly at all, even the rare ones. I had a '70 Mark Donahue Special Javelin too, one of only about 500 made for homologation requirements for Trans Am roadracing.
Man, it was enough trouble just getting some respect for the cars. Most thought they were dogs, that is, until you pulled up next to say a 454 Camaro in a 390 AMX and then proceed to outpull the Camaro in high gear.......... .......THAT opened some eyes. But most stayed unconvinced the engines could run. They were well aware of it at our local strip though.
We did more than our share of street racing, knocking off big dogs like 426 Hemi, 440 Mopar, 454 GM, 455 Poncho or Olds all the time. We collected 375 hp 396 Chevelles like popcorn kernels. All with 395 (.030" over 390) inch motors pretty much, later on we ran a 406 based on the 401 engine. We got beat one time by a Reher/Morrison (yeah, them guys, the national Pro Stock winners, they were based in Arlington next door) 420+ inch SBC '65 Chevy II once, the guy was neutral starting an ATX since he didn't have a good converter in it yet. I was gritting my teeth every time he brought it up to what sounded like 8000 on his launches, expecting the trans to grenade. That was the only time we ever got beat in 3-4 years of street racing.