I swapped the engine (less intake manifold) from an 1985 740 turbo into an 1988 760 turbo. The 85 had a single wire going to the temperature sender and the 88 had two wires going to the temperature sender. Unfortunately the 88 2 wire sender is not compatible with the 85 head and leaks profusely even if I put pipe tape on the threads. This is not surprising since the seal appears to be achieved by a smooth taper and the threaded portion is not a pipe thread. The hex on the sender contacts the block before the taper seats on anything. This is the only thing preventing the car from going back on the road.

Is there a way to use the 85 single wire sender in the 88?

Is there a 2 wire sender that will fit the 85 head without leaking?