Buick oil pressure sensor and guage

I just replaced the engine in my 1997 buick lasabre, with a 2000 chev engine. Both are 3.8 engines. The engine that came out of the car has a 2 wire oil pressure sending unit feeding a pressure gauge. The sending unit is bad and the only sending units at the parts places are 3 or 4 wire. No one has heard of a 2 wire unit. What can I do