The transmission model identification is located on a label or tag on the transmission case. If this label is missing or unreadable, use the service parts identification label in order to identify the vehicle's transmission.
All engines and transmissions, as well as removable roof panels are stamped or laser etched with a partial Vehicle Identification Number (VIN), which was derived from the complete VIN. A VIN derivative contains the following nine positions:
A VIN derivative can be used to determine if a vehicle contains the original engine, transmission or removable roof panel, by matching the VIN derivative positions to their accompanying positions in the complete VIN:
The 6-speed manual transmission, the Borg Warner T-56 (RPO MM6), is stamped with a VIN derivative on the LH side of the transmission case.
The 4-speed overdrive automatic transmission, the Hydra-Matic 4L60-E (RPO M30), is stamped or laser etched with a transmission identification number and a VIN derivative.
The transmission identification number provides the transmission model and when it was built. The transmission (ID) number is located on the bottom of the case just rear of the oil pan.
The VIN derivative will be placed in one of four locations illustrated.
The HYDRA-MATIC 4T40-E transmission has a metal identification nameplate (1) attached to the case exterior.
The information on the nameplate assists the technician in servicing the transmission and ordering replacement parts from a GM Parts Catalog.
Additional transmission identification information is provided on the Service Parts Identification label. This label shows the Regular Production Options (RPO) as well as the standard and mandatory options. This label is affixed to the inside of each vehicle at the assembly plant. Refer to General Information for label location and additional information.
