G 3500 1 Ton Van V8-454 7.4L (1989)
Figure 1 - HYDRA-MATIC 4L60 Transmission Identification Information
DATE OF PRODUCTION CHANGE: (Figure 1)
Beginning March 28, 1990 (Julian Date 087), all HYDRA-MATIC 4L60 transmissions were built using the new low and reverse clutch wave plate.
SERVICE MANUAL REFERENCE:
Refer to the Automatic Transmission Unit Repair Section of the appropriate service manual for low and reverse clutch plate removal and installation
information.