Trans-Am info for the 1966 Barracuda

Might consider running a Ford 9" bearing housing on the end of your 8 3/4 rear. You will probably run a custom width rear anyways. Consult Dr Diff on that.

Or might consider running a floater setup but that would put you with 1970 rules??

Mopar Performance offers a aluminum rear end housing. They do not look stock at all. And I don't think ever was "legal" in Trans Am. Even though I was told by Gurney team members they ran aluminum housings sprayed with cast iron to be magnetic.

I'd think whomever your car builder uses for Ford/Chevy road race leaf springs can make a set for this Barracuda. They are just unequal length with the front segment shorter than the rear. Some advantages to that, but same theories apply.

Also you will convert the car to 4.5 x 5 wheel lug pattern. The 73-76 A-body spindles have the larger bolt pattern and have a larger inner bearing. You will need 73-76 A-body upper control arms if you have to stay stock uppers, or plenty of tubular aftermarket choices. Or just build your own. There is also a disk spindle for F/M/J bodied Mopars that is a little taller and a little lighter.

Both those spindles accept the common racing K727 upper ball joint. So they take a $12 screw in receptacle from Circle Track supply houses. From the Circle Track industry you can buy rebuild-able upper ball joints which you can change the ball joint pin height to effectively change the spindle upright height geometry.