My car was destined for the european market so it never "benefitted" from those updates. Funnily, the chassis reinforcements appeared for a while in '71, then disappeared again sometime in '72 ? So, mayby they figured they were not needed anyways.
My car, and I think all cars before chassis 285, also avoided the frontal-impact reinforcements introduced after the first crash test. I counted 26 reinforcemnets that are MISSING from my car compared to after chassis 285 !!!! The reinforcements are primary in the front and inside the capin towards the trunk. So, the early cars are somewhat lighter - but, DON'T get into a head-on accident
On the other hand, the earlies cars were heavily reinforced around the suspension/coil-over mounts front and rear, something that disappeared when they tooled for production in 71. Then, when the early '71 cars arrived in the US, they re-introduced some of them (well they were different) again. They, of course disappeared again later on in '72.
Did they have any idea of what they were doing?
Kristian