the 72-74 4x4 truck 8 3/4 I have is 59" flange to flange with spring perch center at 43" had the 5 on 5.5 wbp

same as my 76-78 Newport/c-body 8 3/4 59" flange to flange with the 5 on 4.5 wbp and I was able to swap them. (spring perch not the same center)

the 67 polara/c-body 8 3/4 I have is 55" flange to flange and tucks a 10" rim real nice in the fender also.

I run the A-body 8 3/4 52" flange to flange IIRC in my 88-440 truck spring perch centers are 43" same as truck. with the shackle flip it bolts right in on top of springs with car shock plates, tucks a 12" wide rim with 4.5 backset with a 29x15x15 M/T in the fenders with tub work. no wheel hop with my fattys