Does anyone know the threading size for the differential drain and fill plugs. I tried to measure them and came up with 27x2.0 but apparently this was incorrect. My "Thread Detective" doesn't go this high.

12 minutes ago, Jeff Berk said:

Does anyone know the threading size for the differential drain and fill plugs. I tried to measure them and came up with 27x2.0 but apparently this was incorrect. My "Thread Detective" doesn't go this high.

Not near my car right now, but 27 x 2.0 sounds very close to SAE 1.0625-12UN thread. A common size for fittings

https://www.machiningdoctor.com/threadinfo/?tid=120

Edited April 15, 2024Apr 15 by CanTechZ

Says here 1/2 NPT...

https://www.zdriver.com/forums/240z-260z-280z-s30-forums-9/transmission-differential-drain-plugs-37496/

I wonder if it's actually 1/2-inch BSPT? They are almost interchangeable.

If it is 1/2-inch NPT I should have one locally available.

@Jeff Berk, Are you trying to do something that’s not Stock? If so I totally understand. If not why not go to the local Nissan dealer with a p/n from CarParts Manual and order what you need. Forgive me here if I missed something.

10 hours ago, Yarb said:

@Jeff Berk, Are you trying to do something that’s not Stock? If so I totally understand. If not why not go to the local Nissan dealer with a p/n from CarParts Manual and order what you need. Forgive me here if I missed something.

This is related to a project on another thread. I'm having a custom diff cover cast and need to tap it to accept the OEM plugs.

Sorry about that. I totally didn’t put two and two together.

My understanding is that the tapered hardware used elsewhere on the Z's is BSPT. So my expectation is that the original plug on the diff is BSPT as well.

That said... I sure wouldn't fault you if you decided to use NPT instead of BSPT for a full custom part of your own design. I probably would.