help with 66 valiant rear axle

The small bolt pattern 7.25 rears are dirt cheap by comparison. The hard part is finding one that isn't just as well worn as the one you have.
Without doing the research I'm going to say the bearing, etc.. to refurbish the unit are easier to find than the brake drums on it.
The following is from my experience... A parts yard is going to torch cut U bolts, park brake cables, everything, to remove the axle so the labor in R&R to your car will be quite a task.
On the other hand, you could drop the unit you have at the spring hangers, properly remove those other attachments, and refurbish it. The 35 bucks for new U bolts could be better spent.
I did read you comment about your ability but I'm not buying it. If you can read and follow instructions you can do anything.
If you should find that just replacing one outer bearing will buy some time, that's fine too. It's been done a million times before.