1965 GTO Rear Axle Codes

Differential Ratio Std. Axle Code Std. Axle Sticker Code Safe-T-Track Sticker Code
3.08
D
WE
YE
3.23
K
WF
YF
3.36
E
WG
YG
3.55
F
WH
YH

The following ratios were available with heavy duty metallic brake linings.

Differential Ratio Std. Axle Code Std. Axle Sticker Code Safe-T-Track Sticker Code
3.08
G
XB
ZB
3.23
L
XF
ZF
3.36
M
XG
ZG
3.55
N
XH
ZH
3.90
P
N/A
ZK
4.33
S
N/A
ZL

A sticker with the code was applied to the left brake drum.
The code was also stamped on the axle housing directly to the right of the carrier case and below the brake line clip.