Does anybody know the thread pitch, or what size thread tap I'd need to make the stock D30 fill plug work on a custom cover I'm working on?

I was told it was a 3/4" NPT thread, but I ordered a tap from eBay, and it is definitely too big. I have about 10 days to finish building this whole axle and this cover and need to figure this out ASAP! Hoping that somebody knows.

Thanks!

 

Hopefully someone else can confirm, but I'm pretty sure its 1/4" NPT, which would make the thread O.D. just over 1/2".

 

believe it's 1/2" NPT

 

Take the fill plug to a shop and have them check it

 

Take the fill plug to a hardware store and use their thread gauge in the nut/bolt section.