This was definitely a boring day. I just figured out that Kubota ie Universal Diesels use British Standard Pipe Threads (BSPS) which are very close to our NPT threads - but mostly different. Their Oil Pressure Sender "looks" like an 1/8 -27 NPT but is actually a 1/8 - 28 BSPT. Close! You can Google BSPT and see the differences. It turns out that the 1/8, 1/4 & 3/8 are all off by one thread per inch but the 1/2 and 3/4 are the same as our NPT. There is also a "thread form" difference but that blew over my head. So what to do if you want to plumb in an oil pressure gage in a Universal M25? Being the dumb engineer I am, I didn't know they were different, and just forced them together tight with thread sealant and they are holding just fine. A much better approach would be to use thread adapters built for just this purpose, which I think are available from Swagelok. For a short discussion on this subject look at http://www.practicalmachinist.com/vb/showthread.php?p=899130. I didn't know I wanted to know all this, but today that was my chore. Off to the movies.