COPO 9511

[big gear head]

Originally Posted by Pat70Z

Looks like it's been a while since anyone posted on this thread, but I have questions.
In going over my recently purchased 1970 Z28 I found I do not have a COZ or COO coded differential. Sometime in the last 54 years the differential was swapped. It has also been re-geared to 3.55. What I have is something that may be of interest to the folks on this forum.

Differential tube stamp: BW 0429 G2
- 4.56 12 Bolt April 29 Second shift, Detroit Axle Plant

Casting Number: 3894860 NF
- 1967 - 69 Camaro (also 68-70 Nova)

Casting Date: D 189
- April 18, 1969

wheel mount to wheel mount: 60.00 inches = 1967-69 Camaro

Research says the 4.56 was not available as a standard option in 1969 and was only available with a COPO 9511 option.

The '69 housing is 2.5 inches narrower than the 1970 Gen 2 version. I will be searching for a correctly coded COZ housing for my 1970 Z. If someone has need of a 1969 BW coded differential housing, let me know.

The '70 ('70-'81 61 inches) rear end is exactly 1 inch wider than the '69 ('67-'69 60 inches) rear end. There is a lot of completely wrong information about rear end widths on the internet. The spring perches on the '70 rear end are 2 1/4 inches farther apart than the '69, so if someone put a '69 rear end in your '70 then they had to move the spring perches.