8 3/4 housing question

crawsfire said
Rear Axle widths, drum-to-drum:
A BODY ’66-’72: 57-1/8″
Spring perch widths (center-to-center)
A-BODY '66-73= 43"
64 and 65 will have the same dimensions as a 66, they aren't listed because the 8 3/4 wasn't offered those years.

Thanks so much all the members here have been so gracious with their time and knowledge. I’ll be buying the rear this weekend. Thanks everyone.