[Walt Fricke]

The sender uses M10x1.00 thread. However, it screws into an adapter. The parts catalog shows an 18mm crush washer, so it certainly isn't an M12 thread. It has to be an 18. 1.5 is a likely pitch, but you just want to measure it.

Which threads are buggered? The ones in the middle of the adapter? If so, just get another adapter.

The ones in the mag case itself? That's trickier, but you have lots of options. Timecerts or Helicoils (plenty strong for the job) should work, but you may be better off having a shop do this - they will already have the special tools, and you may never need them again. I used a Helicoil on an aftermarket aluminum case oil sump drain plug, and it doesn't leak - the sealing is done by the crush washer, not the threads. Or a machine shop could easily make a larger adapter, and drill and tap your case for it.

As you must have guessed, the adapter is there because that oil passage is drilled/finished all the way from the top of the case down and out the bottom, but the senders use a smaller threaded section.