CHEAPest way to convert rear axle bolt pattern to big bolt pattern???

Look for a usable '73-'76 BBP A-body axle. Most people just give 'em away or don't want much for them, unless they are packing a LSD (freak of nature, and yes, I do have one in my shed). Do a fresh set of axle bearings and seal and be done with it

I was under the impression (looking for the post where I read/mis-read) that the pre-'67 A-bodies had a narrower rear end than the newer ('73-'76) A-bodies. If the width is the same then I will just locate and install one of the newer rear ends.

Does everyone agree that the rear end width is the same on the early A's as the later A's?

This reasoning is what brought me to ask this question to begin with. I wanted to just swap to a newer rear-end but thought I had read somewhere that they were different widths. If they have the same width and same perch locations then I will happily go that route with the bigger 10-inch drums.

PS: Share your terminology definitions:
"Rear-End": the entire rear axle assembly with pumpkin (differential)
"Axle": the machined rods that insert inside the axle tubes (part of rear end) that engage in to the differential and have the hub/lugnuts on the other end.

...This is my first foray into these types of vehicles and I want to make sure I'm not complicating this discussion by mis-labeling something.