Oil Pressure Sender for Westach Gauge

The single wire senders are variable resistance.

The 3 wire sender are variable Voltage.

They are Not interchangeable.

Is your gauge 100 psi or 150 psi???

A UMA N1EU100G (100 psi) should work.  The N1EU150G is 150 psi (10Bar)

It comes in 3 different calibrations.

Be sure to confirm that you are getting the 0.5v-4.5v version.

The UMA sender is 1/8 NPT and the engine may be M10x1.0 thread. 

But check your specific engine.  They used to be 1/8 NPT, the newer ones are M10.   Close enough to cross-thread believing it will fit.

Adaptors are commonly available from auto parts stores for half the price of the aviation suppliers.