Rearend Decode 1967

Q: Rearend Decode 1967

I would like to know how to tell if the rearend of my 1967 car is original to this particular model year, what can i look for on the housing that will help me identify the original numbers’s matching rear.

A: From the 1967 Firebird Supplement to the 1967 Pontiac service manual:

“Eight different axle ratios are available from the Firebird models. They can be identified by the two-letter code stamped on the rear of the L.H. axle tube”.

Here are the codes:

XB – 2.56 open
XC – 2.78 open
XD – 2.93 open
XE – 3.08 open
XF – 3.23 open
XG – 3.36 open
XH – 3.55 open
UN – 2.56 limited slip
UP – 2.78 limited slip
UR – 2.93 limited slip
US – 3.08 limited slip
UT – 3.23 limited slip
UV – 3.36 limited slip
UW – 3.55 limited slip
UX – 3.90 limited slip

If the rear end is original, the two letter code will tell you what axel ratio you have and whether it is an open or limited slip rear end.

A: In 1967, there was no “XL” code for the Firebird Axle….there was however, a “YL” code which was for the 4:33 ratio. Only 13 Firebirds received the 4:33 axle in ’67; none of them were Ram Air cars. There was an “XL” code axle for the ’65 GTO… Std.Axle w/Metallic Brakes and I believe that Camaro used an “XL” code though, not positive.

Any proposed updates, changes, pictures, and/or corrections, please use our comment section below (may need to click on permalink to access comments feature). Information is subject to change and offered as is without any warranties or guarantees. Please review our Term's Of Use for more information.