I bolted a Firm Feel rear bar in my '70 , but I'm using a '68 B-Body Dana with Dr Diff's inset hanger kit.

There's no reason you can't bolt one in to your car too. The chassis mount brackets slip over the frame and are screwed on to hold. The bar end mounts simply sandwich above the springs and between the rear end housing.

Call Firm Feel and tell them you need a rear bar & installation kit for your wider rear end. The bar ends need to reach to the middle of the leaf spring.

You can see the end links in this photo.

slapper bar 4.jpeg
1970 Plymouth 'Cuda #'s 440-6(block in storage)currently 493" 6 pack, Shaker, 5 speed Passon, 4.10's
1968 Plymouth Barracuda Convertible 408 Magnum EFI with 4 speed automatic overdrive, 3800 stall lock-up converter and 4.30's (closest thing to an automatic 5 speed going)