Hello gmbellew, im in need of more info on this topic....please elaborate. But first ill try to cover most about the truck and situation and hopefully you may be able to enlighten me.....so i have 81/84 4x4 3/4 running gear, it has aftermarket 383 with built 700r4, and a 208 tcase. I went with a new wire harness. My i/p is all aftermarket gauges all wired through harness and i decided to go with gps speedometer. So regarding vss and drac and tcc lockup relay is what im curious about.......the new harness doesnt have provisions for add ons like (tcc relay) or anything for that matter, but ill try to stay focused. So if i have no need for vss or drac, do i need to wire in tcc lockup relay ? Because im not sure how to even wire it in but i thought because it is original to the truck and trans type it would be necessary....also its 700r4 with a pigtail for manual lockup that i need to wire, but really dont want to have yo worry about keeping track of when or when not to flip switch.....any help is greatly appreciated.