OD transmissions are scarce and expensive, and if you're wrecking-yard scavenging, try to get the OD relay and kickdown switch off the donor vehicle with the transmission, if possible. (Not the solenoid attached to the trans, the relay in the vehicle wiring harness). New ones aren't available, to my knowledge. It's possible to cobble up a relay using newer parts, but it's difficult. You'll need a heavy-current relay with normally-open and normally-closed contacts. Good luck!
Jerry
