8 3/4 Rear End 66 Valiant

The aftermarket shock plates I looked at do not have the big stud welded on to mount the shock to, they require a bolt on the bottom as well so just make sure you get some good grade 8 hardware and you should be good to go. FWIW, I found a driveshaft from a Charger is a good start with a 741-case center chunk but as was previously stated will need to be shortened. I can't remember the exact measurement but just break out the tape measure. Since you have a 66, you should have the slip yoke at the front instead of the older ball-and-trunnion setup which opens up your options significantly. I was able to do the swap to the 8 3/4 by myself in a carport with just hand tools so it's not very difficult. Your ring-and-pinion choices are limited for the 741 chunk. However any 8 3/4 chunk will bolt in, but you may need a special u-joint depending on what driveshaft you are using.