1964 GTO Axle Codes

Differential Ratio	Std. Axle Code	Std. Axle Sticker Code	Std. Axle Code Color	Safe-T-Track Sticker Code	Safe-T-Track Color
3.08	D	2D	Orange	3D	Green-Yellow
3.23	K	2K	Brown	3K	Green-Brown
3.36	E	2E	White	3E	Green-White
3.55	F	2F	Blue	3F	Green-Blue
3.90	H	2H	Plain	3H	Green-Plain

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

Differential Ratio	Std. Axle Code	Std. Axle Sticker Code	Std. Axle Code Color	Safe-T-Track Sticker Code	Safe-T-Track Color
3.23	L	2L	Brown	3L	Green-Brown
3.36	M	2M	White	3M	Green-White
3.55	N	2N	Blue	3N	Green-Blue
3.90	P	N/A	N/A	3P	Solid Green
4.30	N/A	N/A	N/A	N/A	Black

A sticker with the code was applied to the left brake drum.
The color code was painted on the top of the rear end and axle hubs.
The ratio was stamped on the right rear axle tube.

1965 GTO 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.

1966 GTO Axle Codes

Differential Ratio	Std. Axle Code	Std. Axle Sticker Code	Safe-T-Track Sticker Code
3.08	F	WE	YE
3.23	G	WF	YF
3.36	H	WG	YG
3.55	K	WH	YH
3.90	P	N/A	ZK
4.33	S	N/A	ZL

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
3.23	M	N/A	ZF
3.36	T	N/A	ZG
3.55	W	N/A	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 in the axle housing to the right of the carrier.

1967 GTO Axle Codes

Differential Ratio	Std. Axle Code	Std. Axle Sticker Code	Safe-T-Track Sticker Code
2.78	D	WC	YC
2.93	E	WD	YD
3.08	F	WE	YE
3.23	G	WF	YF
3.36	H	WG	YG
3.55	K	WH	YH
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 in the axle housing to the right of the carrier.

1968 GTO Axle Codes

Differential Ratio	Std. Axle Code	Std. Axle Sticker Code	Safe-T-Track Sticker Code
2.78	D	WC	YC
2.93	E	WD	YD
3.08	F	WE	YE
3.23	G	WF	YF
3.36	H	WG	YG
3.55	K	WH	YH
3.90	P	N/A	ZK
4.33	S	N/A	ZL

A sticker with code was applied to the left brake drum.
The code was also stamped in the axle housing to the left of the carrier.

1969 GTO Axle Codes

Differential Ratio	Sales Code	Non Safe-T-Track Code	Safe-T-Track Code	H.D. Safe-T-Track
2.56	C	WB	XB	N/A
2.78	D	WC	XC	N/A
2.93	E	WD	XD	N/A
3.08	F	WE	XE	N/A
3.23	G	WF	XF	N/A
3.36	H	WG	N/A	XG
3.55	K	WH	N/A	XH
3.90	P	N/A	N/A	XK
4.33	S	N/A	N/A	XM

A sticker with the code was applied to the left brake drum.
The code was also stamped in the axle housing to the left of the carrier.

1970 GTO Axle Codes

Differential Ratio	Sales Code	UPC Code	Non Safe-T-Track Axle Code	Safe-T-Track Code
3.07*	R	GX1	WT	XT
3.08	F	GU4	WE	XE
3.23	G	GU5	WF	XF
3.31*	T	GX2	WU	XU
3.55*	W	HO2	WH	XH
3.90	P	GU8	N/A	XK
3.90	-	-	WK	YK
4.33	S	GU9	N/A	XM
4.33	-	-	N/A	7N

* These ratios were offered with the optional 12 bolt rear end(455 only)
A sticker with the code was applied to the left brake drum.
The code was also stamped in the axle housing to the left of the carrier.

1971 GTO Axle Codes

Differential Ratio	Non Safe-T-Track Axle Code	Safe-T-Track Code
3.07*	WT	XT
3.08	WE	XE
3.23	WF	XF
3.31*	WU	XU
3.55	WH	XH
3.55*	WV	XV
3.90	N/A	XH
3.90*	N/A	XK
4.33*	N/A	XM

* These ratios were offered with the optional 12 bolt rear end.
A sticker with the code was applied to the left brake drum.
The code was also stamped in the axle housing to the right of the carrier.

1972 GTO Axle Code

Differential Ratio	Non Safe-T-Track Sticker Code	Safe-T-Track Sticker Code
3.07*	WT	XT
3.08	WE	XE
3.23	WF	XF
3.31*	WU	XU
3.55	WH	XH
3.55*	WV	XV

* These ratios were offered with the optional 12 bolt rear end.
A sticker with the code was applied to the left brake drum.
The code was also stamped in the axle housing to the right of the carrier.

1973 GTO Axle Codes

Differential Ratio	Non Safe-T-Track Sticker Code	Safe-T-Track Sticker Code
3.08	AD	CD
3.23	AE	CE
3.42	AJ	CJ

A sticker with the code was applied to the left brake drum.
The code was also stamped in the axle housing to the right of the carrier.

1974 GTO Axle Codes

Differential Ratio	Non Safe-T-Track Sticker Code	Safe-T-Track Sticker Code
2.73	JA	JM
3.08	JB	JN

A sticker with the code was applied to the left brake drum.
The code was also stamped in the axle housing to the right of the carrier.