I'm gonna guess between 5.75"-6" but you'll need to measure to be sure.
I'm having some 18x10 rears made for my '70 SS454 as we speak and the b/s is 5.75".I'm running 295/35's just to be safe (and because I didn't want to cut up the car).My original plan was to run 335/30's.
Drop Jon a line @
www.driverzinc.com and see what his data says...
