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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.
Humans, show your math skills: *
+ 4 = nine
Ring & Pinion Gears
Installation / Repair Kits
Replacement Axle Shafts