Help with manual oil pressure gauge - what adapter for the block?

[planters49]

I'm installing an oil pressure gauge in my '84 318i to check the oil pressure. I got a manual oil pressure gauge (not electrical) from advanced auto parts, but none of the fittings will screw into the block where the stock oil sender screws in. The parts place doesn't seem to have an adapter that will fit or the hardware store. What size do I need and where can I get one?

[george graves]

M12 x 1.5. Stewart Warner makes the best ones.

[planters49]

thanks so much for the help!