My worry is the rear u-joint set-up with the caps bolted to the yolk. When I had Driveline Specialists make my new driveline, they told me I should try to replace the yolk with a heavier duty set-up, but I said I was gonna leave it pretty stock under the hood,,,,,, WRONG!! Now I am asking you guys if this is the weak link in my set-up. Should I find a yolk that will fit a Dana 44 with a heavier duty rating?  I just learned tonight by browsing the search that a 65-66 Mustang rear will drop right in, so decisions, decisions.

                    Thanks,  Bud in Arizona 

It will depend on your intended use of the car.  If you are going to put slicks on it and run it every week at the drags, then a stronger yoke would be probably wise.  If you are using street tires and using the car for cruising, then the u-joint should hold up.  I would assume that a yoke from a '56 Dana would bolt onto the '55 pinion.  Wagons, sedan deliveries, Mercurys, and police cars also used Danas, so you are not restricted to T-Birds for a donor.  You might also look into chevy S10 yokes, I have heard they use Dana 44s, at least in the 4wd models.  Might fit the '55 pinion.

The majority of V8 early mustangs used the 8" rear, which is probably no stronger than the Dana, but they do have the larger u-joint.