IIRC, the '95 and earlier versions are the ones to look for because they are easy to wire.

The non-lockup units will have two pins (contacts) towards the back of the main case just ahead of the rear oil line port. It needs one fuse protected hot wire and one switch controlled ground wire to control OD. Mine came from a 91 Ram 5.9 Reading-bodied work truck.

The lockup units will have three pins towards the back of the main case just ahead of the rear oil line port. It needs one fuse protected hot wire, one switch controlled ground wire to control OD and one switch controlled ground wire for LU.

I think after '96, the 518s are controlled by electronics and would be hard to adapt to an older car.