4x4 rear axle housings. Are they all the same

[GMC-YA68]

You guys school me. Are all the 4x4 rears(12 bolt) (6-lug) the same? Excluding gear ratio of course but are they all 100% interchangeable or were there differences?

Differences in trucks compared to blazers?

['68OrangeSunshine]

Originally Posted by GMC-YA68

You guys school me. Are all the 4x4 rears(12 bolt) (6-lug) the same? Excluding gear ratio of course but are they all 100% interchangeable or were there differences?

Differences in trucks compared to blazers?

The First Generation K/5s were basically cut-down K/10s and had the same axles as K/10s. Some early standard blazers had 250 L6s and a Dana20 XFER case. But most 1st Gen K/5s were rigged just like the light duty 1/2 tons in the Driveline/Differential department.
\There are differences between Coil Spring and Leaf Spring, 4X2 Drive and 4X4, Early and Late widths, , Disc Brake or Drum Brake. Then there's manufacturers: Eaton [GM], Dana, H.O.?
I gotta '71 Jimmy 4x4 K/1500. It had an Eaton Posi 12-Bolt Corp in 3.73.
It blew up. So I pulled the Corp 12-Bolt off my [fallow] '67 Suburban K/10, a 3.73 rear axle that had been major-overhauled in the summer of 1995 and an Auburn Posi added on. Due to circumstances beyond my control, I had to get Moser axles cut for my length and spline count. So that went under the '71, after we updated the drum brakes to the bigger finned drum.
I did notice a difference in spring perch locations, between a '67 and a '71. One was wider. Can't remember which.
The '67 rear has been made to fit on the '71 and runs good, but we never could get the '71 axle on the '67 springs, so it's been bailingwired on for many months. Until I can rebuild a 454, it's not going anywhere soon.