Rear suspension old vs new style

[georgeramos]

its time to replce the rear suspension on my 71. The meahcnic i had inspect it for me said i should switch to the new style when i do the swap. is that the generally acceptable method? What are the benefits of the new style over the old?

Thanks

George

[azruss]

The new style is heavier by about 30#. It has a flange on the end of the axle for mount wheel concentric. The backer plate to the disc brakes is much heavier and with bigger bolts.
The true issue is that it is geared taller than a 71 diffy. This means you will turn less rpms at speed, but will hurt your quickness with the small motors.
It also requires a new style drive shaft and your speedo wont be accurate without replacing the speedo drive and the associated gear inside the tranny.
I have an 80 FI and i put in a 71 tranny and diffy.

[vandor]

Russ, I think his mechanic meant the trailing arms, not the rear end.

The later trailing arms have stronger bushings, and are more expensive. The OEM upper ones had a bad habit of popping off the bushing.