Transmission ZF S6-650/6S-750. Troubleshooting Guide-Service Tips. ZF Industries. DESCRIPTION AND OPERATION. Manual Transmission and Clutch. Manual Transmission. The S6-650 ZF transmission is a six-speed synchronized unit. The ZF six speed has the following features: ○ An integral clutch housing. ZF Industries, Inc. S6-650 Six Speed Manual Transmission Vehicle Transmission Technology Service Manual Author: Michael S. Paterson Page 1 of 48 GM Service With SYNCHROS. for theFORD ZF truck 6-speed manual transmission equipped withS6-650 / S-650. 8 CYL 5.4L 2002-ON - 6spd, RWD or 4WD ( ZF S650, aluminum case,ZF Industries, Inc. Vehicle Transmission Technology. S6-650 Six Speed. Manual Transmission Service Manual. Disassembly and assembly of subassemblies:. For theFORD ZF truck 6-speed manual transmission equipped withS6-650 / S-650. FORD: F-SERIES TRUCKS (F250, F350, F450, F550 - SUPER DUTY) P-SERIES VAN and