I've read the (stock) 41" Chevy-bars were prone to rust and the aftermarket ones somehow solved that by making shorter (?) 35" bars.
I like to know what kind of setup these cars use to be able to simply run a 6" shorter torsion bar without any other mods...??

It's those shorter 35" bars I would be interested at because I have an A-body (and a few C and older Mopars).
But chances are still very slim to find a Chevy with replaced shorter 35" bars in a junkyard (here in Europe even less likely).