Diff crossmember bolts
 

So a few months ago I started my winter z projects, among them was the install of an RT diff mount, which involved removing the crossmember that held the previous diff mount.

When I took this off, three of the four bolts were 14mm, the last one however was 15mm, and was quite loose. As I was reinstalling the crossmember, I notice that this bolt hole is actually stripped.

So my plan is to take one of the existing (correct) bolts to a fastenal and get the next larger size metric bolt with the same thread pitch, and a drill bit and tap to match. Drill the hole, tap it and then reinstall.

Should work, right?

Yes for sure you can drill out out and retap it. As long as there is enough meat there to do so. If you are doubtfull, you could always helicoil it.

15 mm is not a standard thread size. Are you measuring the wrench size or the thread O.D.? Could even be a S.A.E. thread someone used for the repair.

the wrench size... that's how I realized something was amiss... didnt realize the scope of the issue until I was putting it back together... I think the bolts are M10x1.5... guessing, havent measured.

Don't assume the bolt size is bigger. Just about all the aftermarket bolts of the same size come with a larger bolt head size.

You should be looking for a 10mm bolt thread size. A 10mm bolt typically has a 15mm hex head but on the Datsun Z cars most 10mm thread bolts have 14mm hex heads, also known as JIS bolts. These smaller heads often help in tight areas where a larger head or wrench will not fit. Here is an example of JIS 10mm:

https://zcardepot.com/suspension/rea...260z-280z.html