The most  inclusive G3 rear axle information on the internet! If you have any questions, comments, or corrections, feel free to PM one of the Admins.


RPO Codes:

G80	Axle Positraction, Limited Slip
G81	Positraction Rear Axle
G82	Axle Rear			4.56
G84	Axle Rear			4.10
G86	Axle , Rear, Limited Slip
G87	Ring Gear, 8.50 Inch
G89	Ring Gear, 7.50 Inch
G90	Rear			3.15
G91	Special Highway Rear Axle			3.08
G94	Axle Rear			3.31
G96	Axle Rear			3.55
G97	Axle Rear			2.73
GH0	Axle Rear			3.54
GH2	Axle Rear			2.29
GH3	Axle Rear			2.77
GH4	Axle Rear			2.92
GH7	Axle Rear			2.73
GJ1	Axle Rear			5.38
GJ2	Axle Rear			5.13
GK7	Axle Rear			4.78
GK8	Axle Rear			4.33
GK9	Axle Rear			4.63
GL0	Axle Rear			5.13
GL3	Axle Rear			6.17
GM1	Axle Rear			2.59
GM2	Axle Rear			3.44
GM3	Axle Rear			3.45
GM4	Axle Rear			3.67
GM5	Axle Rear			3.89
GM6	Axle Rear			4.22
GM7	Axle Rear			3.68
GM8	Axle Rear			2.56
GN9	Axle Rear			4.11
GS1	Axle Rear			2.73
GS3	Axle Rear			3.73
GS4	Axle Rear			3.70
GS5	Axle Rear			4.11
GS6	Axle Rear			4.56
GS8	Axle Rear			3.94
GT1	Axle Rear			2.56
GT2	Axle Rear			2.29
GT4	Axle Rear (DUP WITH 5 X 1)			3.73
GT5	Axle Rear (DUP WITH GT8)			4.10
GT7	Axle Rear			3.33
GT8	Axle Rear (DUP WITH GT5)			4.10
GU1	Axle Rear			2.41
GU2	Axle Rear			2.73
GU3	Axle Rear			2.93
GU4	Axle Rear			3.08
GU5	Axle Rear			3.23
GU6	Axle Rear			3.42
GU7	Axle Rear			2.77
GU8	Axle Rear			3.90
GU9	Axle Rear			3.91
GV0	Axle Rear			3.55
GV1	Axle Rear			2.73
GV2	Axle Rear			5.83
GV3	Axle Rear			3.08
GV4	Axle Rear			3.36
GV5	Axle Rear			3.55
GV7	Axle Rear			4.11
GV8	Axle Rear			2.72
GV9	Axle Rear			4.25
GW2	Axle Rear			2.56
GW3	Axle Rear			2.56
GW4	Axle Rear			3.31
GW5	Axle Rear			2.73
GW6	Axle Rear			3.27
GW8	Axle Rear			4.10
GW9	Axle Rear (DUP WITH GU3)			2.93
GX1	Axle Rear			3.70
GX2	Axle Rear			3.07
GX3	TransAxle Final Drive			3.33
GX4	Axle Rear			3.75
GX5	Axle Rear			4.09
GX6	Axle Rear			3.53
GX8	TransAxle Final Drive			3.74
GY2	Axle Rear			3.31
GY3	TransAxle Final Drive			4.29
GY4	Axle Rear			4.53
GY5	Axle Front			3.65
GY7	TransAxle Final Drive			4.18
GY9	Axle Rear			4.31

Rear Axle Code example: CB G 112 1 E
(CB = Ratio, G = Plant, 112 = 112th day of year, 1 = shift, E = Positraction Source)

Assembly Plant Codes
Buick - B
Buffalo - C
Cadillac - D
Detriot Gear & Axle - G
GM of Canada - K
Warren, MI - W
Oldsmobile - O
Pontiac - P
Pontiac/Canada - M

Shift: D or 1 = Day shift| N or 2 = Night shift

Positraction Source/Code:
- = No positraction
D = Dana Positraction Differential
E = Eaton Positraction Differential
G = Chevrolet G&A Positraction Carrier
O = Oldsmobile Positraction Carrier
W = Warren/Warner Motive

Positraction Casting Numbers
Due to the possible confusion with gear ratio descriptions... a HIGHER number is a LOWER gear.
In the below examples, 2.56:1 & down = 2.41, 2.56, etc... which is actually a HIGHER gear ratio.

8.5" "Corporate"
Casting # Series Gearing
410408N 3 2.73:1 & up
410409N 2 2.56:1 & down

rear axle casting date code Rear Housing Casting Date

Example: D143 - (D = Month, 14 = Day, 1 = Last digit of year (1973)).

Month: A = Jan, B = Feb, C = Mar, D = Apr, E = May, F = Jun G = July, H = Aug, I = Sep, J = Oct, K = Nov, L = Dec

Axle Ratio Stamping codes (First two letters):

1973

2.73..............WA
2.73..............AC
2.73 posi........XB
2.73 Posi........CC
3.08..............WC
3.08..............AD
3.08 Posi........XC
3.08 Posi........CD
3.42..............WE
3.42...............AJ
3.42 Posi.........XE
3.42 Posi.........CJ


1974

2.73..............AC
2.73..............CC
2.73..............WB
2.73 Posi........XA
3.08..............AD
3.08 Posi........CD
3.08..............WC
3.08 Posi........XC
3.42..............AJ
3.42 Posi........CJ
3.42..............WE
3.42 Posi........XE


1975

2.56 posi........CH
2.56..............AH
2.73..............WA
2.73posi........XA
2.73posi........CC
2.73..............AC
3.08..............WC
3.08 posi........XC
3.08 posi........CD
3.08..............AD
3.42..............WE
3.42 posi........XE
3.42 posi........CJ
3.42..............AJ


1976

2.56 POSI........CH
2.56 POSI........AH
2.73...............WA
2.73 POSI........XA
2.73 POSI........CC
2.73...............AC
3.08...............WC
3.08 POSI........XC
3.08 POSI........CD
3.08...............AD


1977

2.56.............AB
2.56 POSI.....CB
2.73.............ZE
2.73.............AC
2.73 POSI.....ZW
2.73 POSI.....CC
3.08.............ZJ
3.08.............AF
3.08 POSI.....ZY
3.08 POSI.....CF

Axle Ratio		Tooth Combination
2.56:1		41,16
2.73:1		41,15
3.07:1		43,14
3.08:1		40,13
3.08:1		37,12
3.31:1		43,13
3.36:1		37,11
3.42:1		41,12
3.55:1		39,11
3.73:1		41,11
4.10:1		41,10
4.11:1		37,9