It depends on whether your truck was a gas or diesel truck to start with. If it was gas then your cruise servo is still there. If it was diesel then you need to simply get the cruise servo from a gas truck and hook it up. the wires that will control the servo are hooked up to the PCM in the drivers side fenderwell. you need the 2 wires that came from the cruise buttons on the wheel and the vss+ wire from the PCM. Battery hot, key on hot, brake input, clutch input, ground and cruise indicator light going to the dash. all these are found on the PCM and can then be hooked up to the Cruise servo. This also depends on the year of cummins. if you have a 04. 5 or newer cummins you have a fly by wire setup and there is no manual cable. but an older cummins you should have used the cable setup and you can piggy back the gas servo with the cable throttle.