Picked this up yesterday...

Do you recall the info they needed when you ordered it? For example, did you have to supply measurements, over all, spring perches, shock mounts, etc?

No. I just ordered the axles. I had an A body rear so everything was already in the right place. But it was a small bolt pattern.
It's a standard thing. They know all about it. It's a drop in.
They move the axle flange out a specified amount on the new axles.
IIRC all 8 3/4s came with "obsolete" 2 inch brake shoes.
I think that would be their "A" body brake option on the link below.
Yea. That sounds right.
Modern cars like Diplomats have 2 1/4 shoes so they just make the axles with large bolt pattern and the correct back spacing for those shoes.
So all you need, if you have the A body rear is the axles (bearings seal and whatever) and you can of course use drums off of some newer car.
The "B" body would have the larger brake shoes.
Big bolt pattern.
Moser Engineering - A-Body Axles - MOPAR Car Axles - MOPAR AXLES - Axles - Stock Application

Oh and if IIRC, I paid more like 2-250 or the set.
Things go up.