Conversion Kit: 1973-1987 Chevy®/GMC® Solid Axle with Automatic Transmission to 1989-1998 Cummins® 12-Valve

The 4x4 trucks have a taller transmission tunnel making it a more likely candidate than the 2WD, but the conversion has been done to both. 2WD truck owners have had to do body lifts or tunnel modifications depending on which transmission they wish to use.

Regardless of 2 or 4 wheel drive, you’ll need to drop the cross-member under the oil pan about 2” to clear the taller Cummins engine. It is possible to fit the engine into the truck without modifying the firewall slightly but removing the #6 valve cover will not be possible. Just below the windshield wiper motor you will need to massage the firewall into the cab about ½” – ¾” so it’s not anything major but necessary for valve cover removal after the engine has been fitted into your truck.

Another thing to be aware of if you choose to run the mechanical fan is bending the pinch weld, where the firewall and the tunnel meet, back to make room for the transmission bell housing. You may have to modify the pinch weld all the way across the firewall on the passenger side depending on what diameter exhaust you wish to use. *Uses Ford 6.4 diesel starter*

*Summary: There is fabrication work necessary to make room for the Cummins engine. This includes dropping the cross-member underneath the oil pan*