Front Diff Check drain bolt size

[Lttlwing16]

So I did my 60K interval differential service and unfortunately this time the front diff check bolt brought it's threads with it. So the converter case threads are stripped and the bolt won't torque to spec, so it's leaking diff fluid, and now my Legacy is sidelined. I've located a mechanic locally whos comfortable putting in a Time sert plug so I can continue to use the stock drain bolt.

he needs to know the 1) Diameter of the bolt which I have gathered as 18mm threaded portion, and 2) the threads, which I am unsure of. I believe it to be 1.5. 3) The length is listed on the subaru parts page as 18 x 14.7 (M18 x 14.7mm). 

I'll get over to my subaru dealer on Weds to pickup a new drain bolt for the new insert and can measure it then, but wanted to get a jump on ordering the Time Sert stuff. 

 

Thanks in advance,

David