West Coast Differentials has been distributing quality differential and axle parts since 1982. We believe that our exceptional customer service and product knowledge is what sets us apart from the competition. Give us a try, we think you'll be glad you did!
The most current parts and application information can always be found here on our website or by calling one of our differential parts experts. All of the parts we sell are also used every day in our busy service shop. This gives us confidence in the quality of the parts we sell.
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 codes are arranged alphabetically in rows on the tag, from left to right and top to bottom.
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 Code | Description | Ratio |
| G11 | Transaxle Final Drive | 2.56 |
| G44 | Axle Rear | 3.07 |
| G72 | Axle Rear | 2.14 |
| G75 | Axle Rear | 3.62 |
| G76 | Positraction Rear | |
| G80 | Axle Positraction, Limited Slip | |
| G81 | Positraction Rear Axle | |
| G82 | Axle Rear | 4.56 |
| West Coast Differentials Tech Support / Order Hotline: (800)510-0950 | ||
| Call to Order before 4PM PST and most Parts Ship Out TODAY! | ||
| Find Replacement Axle Parts for your GM Vehicle in our Application Guides | ||
| G84 | Axle Rear | 4.10 |
| G86 | Axle Rear, Limited Slip | |
| G87 | Ring Gear, 8.5″ | |
| G89 | Ring Gear, 7.5″ | |
| 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 |
| West Coast Differentials Tech Support / Order Hotline: (800)510-0950 | ||
| Call to Order before 4PM PST and most Parts Ship Out TODAY! | ||
| Find Replacement Axle Parts for your GM Vehicle in our Application Guides | ||
| 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 |
| West Coast Differentials Tech Support / Order Hotline: (800)510-0950 | ||
| Call to Order before 4PM PST and most Parts Ship Out TODAY! | ||
| Find Replacement Axle Parts for your GM Vehicle in our Application Guides | ||
| 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 |
| West Coast Differentials Tech Support / Order Hotline: (800)510-0950 | ||
| Call to Order before 4PM PST and most Parts Ship Out TODAY! | ||
| Find Replacement Axle Parts for your GM Vehicle in our Application Guides | ||
| 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 of 5X1) | 3.73 |
| GT5 | Axle Rear (Dup of GT8) | 4.10 |
| GT7 | Axle Rear | 3.33 |
| West Coast Differentials Tech Support / Order Hotline: (800)510-0950 | ||
| Call to Order before 4PM PST and most Parts Ship Out TODAY! | ||
| Find Replacement Axle Parts for your GM Vehicle in our Application Guides | ||
| GT8 | Axle Rear (Dup of 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 |
| West Coast Differentials Tech Support / Order Hotline: (800)510-0950 | ||
| Call to Order before 4PM PST and most Parts Ship Out TODAY! | ||
| Find Replacement Axle Parts for your GM Vehicle in our Application Guides | ||
| 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 |
| West Coast Differentials Tech Support / Order Hotline: (800)510-0950 | ||
| Call to Order before 4PM PST and most Parts Ship Out TODAY! | ||
| Find Replacement Axle Parts for your GM Vehicle in our Application Guides | ||
| 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 of GU3) | 2.93 |
| GX1 | Axle Rear | 3.70 |
| GX2 | Axle Rear | 3.07 |
| GX3 | Transaxle Final Drive | 3.33 |
| GX4 | Axle Rear | 3.75 |
| West Coast Differentials Tech Support / Order Hotline: (800)510-0950 | ||
| Call to Order before 4PM PST and most Parts Ship Out TODAY! | ||
| Find Replacement Axle Parts for your GM Vehicle in our Application Guides | ||
| 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 |
| GYS | Transaxle Final Drive | 3.65 |
| West Coast Differentials Tech Support / Order Hotline: (800)510-0950 | ||
| Call to Order before 4PM PST and most Parts Ship Out TODAY! | ||
| Find Replacement Axle Parts for your GM Vehicle in our Application Guides | ||
| H01 | Axle Rear | 3.07 |
| H04 | Axle Rear, Single Speed | 4.11 |
| H05 | Axle Rear | 3.73 |
| H12 | Axle Rear, 21000 Lbs, Eaton 21065S, Single Speed | |
| H42 | Axle Rear | 6.17 |
| H43 | Axle Rear | 5.43 |
| HA3 | Axle Rear, Single Speed | 5.29 |
| HC4 | Axle Rear | 4.56 |
| HC7 | Axle Rear, 7500 Lbs, Single Speed | 2.38 |
| HC8 | Axle Rear, Single Speed, Truck | 3.21 |
| West Coast Differentials Tech Support / Order Hotline: (800)510-0950 | ||
| Call to Order before 4PM PST and most Parts Ship Out TODAY! | ||
| Find Replacement Axle Parts for your GM Vehicle in our Application Guides | ||
| HC9 | Axle Rear | 5.13 |
| HE3 | Axle Rear, 3500 Lbs, Single Speed | 3.07 |
| HE4 | Axle Rear | 3.40 |
| HF7 | Axle Rear, 10000 Lbs, Dana 70, Single | 4.56 |
| HF8 | Axle Rear | 4.88 |
| HJ1 | Axle Rear | 4.55 |
| HJ2 | Axle Rear | 5.86 |
| HJ3 | Axle Rear | 4.75 |
| HJ4 | Axle Rear | 6.50 |
| HJ5 | Axle Rear | 5.57 |
| West Coast Differentials Tech Support / Order Hotline: (800)510-0950 | ||
| Call to Order before 4PM PST and most Parts Ship Out TODAY! | ||
| Find Replacement Axle Parts for your GM Vehicle in our Application Guides | ||
| HJ6 | Axle Rear | 4.78 |
| HJ7 | Axle Rear | 4.88 |
| HK1 | Axle Rear | 2.87 |
| HK3 | Axle Rear | 6.14 |
| HK9 | Axle Rear 10000 Lbs, Single Speed | 5.86 |
| HO4 | Axle Rear | 4.11 |
| HO6 | Axle Rear | 4.63 |
If you are unable to find the GM RPO Codes Label, a GM dealership can usually tell you what you have using the VIN number of your vehicle. Our parts experts can also help you with identification with year, make and model information. We cannot use casting numbers for identification.
Order by Phone
Need Help or Parts ASAP?
For the fastest service, call our Differential Parts Experts at (800) 510-0950 for immediate assistance. We are available to help Monday thru Friday from 8 AM to 5 PM Pacific Standard Time, and most orders placed by 4 PM ship out the SAME DAY!
Contact Us
For inquiries about our products and services, please fill out the form below. We look forward to serving you!
