I never disengage the OD, so the cable's primary use is to hold the lever in place. I just let the OD do it's thing. I also have disc brakes so the freewheel part is not an issue. Your 3/4 ton has plenty of brakes also, so it shouldn't be a problem. You have to remember to shift into reverse when you park and or set the brake or the truck could roll down the street on it's own. There are aftermarket KD switches and relay's available. Send me an email and I can give you some P/Ns and sources.
Fred