Why would you not want the lock-up? From what I've read, you just don't hook up the lockup wiring to run it as a non-lockup. Was the TH350C original to the truck? Seems like if not, you wouldn't have the wiring anyways and therefore you are good to go. Alternatively, you could just wire the lockup to a switch and manually engage it when you want to do 80mph on the freeway