On my 83 chassis with a 84 cab it went like this. The chassis was a factory 6.9 t19 now its a turbo 7.3 zf5 and the cab was originally a F250 460 2wd c6, The manual chassis had a factory jump wire plug where the mpls would connect to bypass the neutral safety switch, The automatic cab had a jump wire plug to bypass the clutch safety switch so it has factory bypasses on both ends lol. You will need to figure out how to bypass the neutral safety switch for the auto and you'll need to pull the reverse light plug from the donor truck and figure out which wires to splice that too. Or if the donor truck is still around grab the whole trans harness if its not around find a plug that fits the reverse light switch and look at some wiring diagrams and wire it up with heat shrink butt connectors