You might want to pull the cruise amp and overvoltage relay. We recently had one appear (same year) at the local pick-a-part and I pulled those items, just because. I currently have a "rebuilt" cruise amp from an '84 300SD in my '87 300TD, so at least some amps will work in other applications. I'll bet the power lock vacuum motor would work to switch your 123 over to the newer style lock system.