Axle Ratio & Identification Code
Rear axle ratio, differential type, manufacturer, and build date information is stamped on forward side of right axle. An RPO code may be stamped on a metal tag attached to differential housing. The service parts identification label will have Regular Production Option (RPO) codes for specific rear axle identification. See Figure . Also, refer to the appropriate AXLE RATIO IDENTIFICATION table.
NOTE:
On Caprice and Roadmaster, 7 1/2" ring and pinion gear has been replaced with 7 5/8" ring and pinion gear. Although axle housing assemblies look alike, internal components are different.