GM RPO Codes – Factory Identification Labels and Interpretation

GM RPO Codes, or General Motors “Regular Production Option” codes contain lots of valuable information about your GM vehicle. Identify your GMC or Chevrolet rear end gear ratio by the RPO Codes, usually located on the placard labeled “Service Parts Identification” inside the drivers door panel or glove box. (Accurate identification using the GM RPO code assumes that the rear end has not been previously modified) The prefix is usually F, G or H when referring to Axle Identification. The list below is a partial list of typical GM RPO Codes, specifically the codes pertaining to Axle Identification, Differential Type and Gear Ratio.

RPO CodeDescriptionRatio
G11Transaxle Final Drive2.56
G44Axle Rear3.07
G72Axle Rear2.14
G75Axle Rear3.62
G76Positraction Rear 
G80Axle Positraction, Limited Slip
G81Positraction Rear Axle 
G82Axle Rear4.56
G84Axle Rear4.10
G86Axle Rear, Limited Slip
G87Ring Gear, 8.5″ 
G89Ring Gear, 7.5″
G91Special Highway Rear Axle3.08
G94Axle Rear3.31
G96Axle Rear3.55
G97Axle Rear2.73
GH0Axle Rear3.54
GH2Axle Rear2.29
GH3Axle Rear2.77
GH4Axle Rear2.92
GH7Axle Rear2.73
GJ1Axle Rear5.38
GJ2Axle Rear5.13
GK7Axle Rear4.78
GK8Axle Rear4.33
GK9Axle Rear4.63
GL0Axle Rear5.13
GL3Axle Rear6.17
GM1Axle Rear2.59
GM2Axle Rear3.44
GM3Axle Rear3.45
GM4Axle Rear3.67
GM5Axle Rear3.89
GM6Axle Rear4.22
GM7Axle Rear3.68
GM8Axle Rear2.56
GN9Axle Rear4.11
GS1Axle Rear2.73
GS3Axle Rear3.73
GS4Axle Rear3.70
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GS5Axle Rear4.11
GS6Axle Rear4.56
GS8Axle Rear3.94
GT1Axle Rear2.56
GT2Axle Rear2.29
GT4Axle Rear (Dup of 5X1)3.73
GT5Axle Rear (Dup of GT8)4.10
GT7Axle Rear3.33
GT8Axle Rear (Dup of GT5)4.10
GU1Axle Rear2.41
GU2Axle Rear2.73
GU3Axle Rear2.93
GU4Axle Rear3.08
GU5Axle Rear3.23
GU6Axle Rear3.42
GU7Axle Rear2.77
GU8Axle Rear3.90
GU9Axle Rear3.91
GV0Axle Rear3.55
GV1Axle Rear2.73
GV2Axle Rear5.83
GV3Axle Rear3.08
GV4Axle Rear3.36
GV5Axle Rear3.55
GV7Axle Rear4.11
GV8Axle Rear2.72
GV9Axle Rear4.25
GW2Axle Rear2.56
GW3Axle Rear2.56
GW4Axle Rear3.31
GW5Axle Rear2.73
GW6Axle Rear3.27
GW8Axle Rear4.10
GW9Axle Rear (Dup of GU3)2.93
GX1Axle Rear3.70
GX2Axle Rear3.07
GX3Transaxle Final Drive3.33
GX4Axle Rear3.75
GX5Axle Rear4.09
GX6Axle Rear3.53
GX8Transaxle Final Drive3.74
GY2Axle Rear3.31
GY3Transaxle Final Drive4.29
GY4Axle Rear4.53
GY5Axle Front3.65
GY7Transaxle Final Drive4.18
GY9Axle Rear4.31
GYSTransaxle Final Drive3.65
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H01Axle Rear3.07
H04Axle Rear, Single Speed4.11
H05Axle Rear3.73
H12Axle Rear, 21000 Lbs, Eaton 21065S, Single Speed
H42Axle Rear6.17
H43Axle Rear5.43
HA3Axle Rear, Single Speed5.29
HC4Axle Rear4.56
HC7Axle Rear, 7500 Lbs, Single Speed2.38
HC8Axle Rear, Single Speed, Truck3.21
HC9Axle Rear5.13
HE3Axle Rear, 3500 Lbs, Single Speed3.07
HE4Axle Rear3.40
HF7Axle Rear, 10000 Lbs, Dana 70, Single4.56
HF8Axle Rear4.88
HJ1Axle Rear4.55
HJ2Axle Rear5.86
HJ3Axle Rear4.75
HJ4Axle Rear6.50
HJ5Axle Rear5.57
HJ6Axle Rear4.78
HJ7Axle Rear4.88
HK1Axle Rear2.87
HK3Axle Rear6.14
HK9Axle Rear 10000 Lbs, Single Spd5.86
HO4Axle Rear4.11
HO6Axle Rear4.63

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