Usage:
The former 785 transmission with the 3YB serial number prefix is identical to the 789 transmission with the 2BE prefix with the exception of the input universal joint yokes and the number of clutch discs used in the No. 1 and No. 2 clutches. These differences have made it necessary to stock two exchange transmissions to support the earlier 785 (8GB1-315) and the 789 Off-highway Trucks. Conversion of a 785 Truck transmission (3YB1-637) to the 789 Truck transmission makes it possible to use only one exchange transmission to support both models.
To convert a 785 Truck transmission to a 789 Truck transmission, add one 9W2473 Friction Disc and one 8P5687 Clutch Plate to each of the No. 1 and 2 clutches. Replace the 9W3904 Clutch Reaction Plate Assembly, used in the former 785 Truck transmission, with a 9W3896 Plate Assembly, used in the 789 Truck transmission. Replace the 1T1565 Yoke, used in the former 785 Truck transmission, with a 7T3115 Yoke, used in the 789 Truck transmission.