I have found that the speed sensor will go AWOL and, although one can drive w/out the speedo and cruise, it's tough w/out the OD
A switch installed somewhere inside the cab can by-pass the VSS and provide the ground circuit for the OS solenoid. I tapped into the wire at the large harness directly on top of the brake booster. It's an easy spot. I used a headlamp hi-low beam switch and mounted it to the floor. Used two of the three terminals. Grounding one to the floor (or under dash).
I can now control OD shift by this floor mount switch or the manual switch on the dash and shifter lever. You guys w/autos are installing the new shifter lever/switch assy .......right!?