Chevelle & Ford Rear End Widths

Lower spring mount on 1966 Chevelle.  A bolt and plate arrangement hold the spring in place and the pigtail is the same general diameter as the rest of the spring.

Lower spring mount on 67 and later Chevelles fit over a tower on the rear end and the pigtail is a smaller diameter.

It has been reported that the 1967 model year could have either type of spring mount but I cannot confirm this

Casting numbers found to be the most prevalent in Chevelle 12-bolt rear ends:

1965 Chevelle 3859140N
1966 Chevelle 3875745N
1967 Chevelle 3894939NF
68-69 Chevelle 3917124NF
1969 Chevelle 3959038NF
70-72 Chevelle 3969278NF

As always, there will most likely be some rumor of overlap in numbers but unless you have a build sheet/Protect-O-Plate and can verify the stamped codes as original, who knows? It should also be noted that the 1965 12-bolt is the only one with the diagonal bracing on the center section casting.

Note: Thanks to David Bates for the above information!

According to an old article, Inside '64 -- '72 A-Bodies, (Car Craft Magazine), 1967 was a transition year in that A-body cars might have a 1964-66 style rear end, a 1968-72 rear end (which is wider, and commonly available), or a "hybrid" rear end, which will have the 60.5-inch width, but with the early spring mounting pad and trailing arm brackets. Several late 1966 rear ends with casting number 3875745, one dated L 8 6 (December 8, 1966), have been found in early 1967 Chevelles and retain the retention plates to secure the rear springs.

Measurements taken on 1967 Chevelle rear end for comparison.

Backing plate to backing plate - 53 5/16-inches (+/-).

Outside drum to outside drum - 60-inches (+/-).