This factory service and repair manual for the 1990 GMC W6500 Forward comes down to one engine: the turbocharged 5.8L inline-six, 353 cubic inches, diesel. Nothing branches on the body side either, since the low tilt straight truck in trim code W6R042 is the only configuration listed. That leaves the book free to go deep rather than wide, since every procedure, specification and torque value in it describes the same truck, and the wiring diagrams follow one harness layout rather than several.
Engines covered
- 5.8L inline-six (353 cu in) — turbocharged, diesel
Body styles covered
- Straight truck, low tilt
Trims covered
- W6R042
Known issues on the 1990 W6500 Forward. The 1990 W6500 Forward has a clean federal record, with no recalls issued against it and no owner complaints logged by NHTSA. In practice the manual is used for scheduled service and for the faults that show up with age on the turbocharged 5.8L diesel, supported by its diagnostics, its published specifications and torque values, and its wiring diagrams for the chassis electrical circuits.
