Seatbelt bolt technical specs needed

I'm trying to find out some specific information about GM seat belt bolts. Primarily the bolts used to mount the belt reels under the back seat. I think they are 12mm bolts. They take either a T47 or T50 torx bit, depending on the year. The same bolt is used for the upper reel mount in the back, and I think the front seatbelt mounts that go into the floor at the 'hump'.

Here's what I'm trying to find out:

What is the true size? Are they 12mm or are they an off-breed metric that's actually SAE?

Grade 2, 5 or 8?

What does the factory say about re-using them. It seems the threads become damaged upon removal. I proved this to myself yesterday, by taking off the mount for the upper reel in the back BEFORE I took out the torx bolt. The exposed threads at the end ot the bolt were fine until they passed through the captured nut on the mount. To me, if the threads are damaged coming out, it could mean additional damage going back in PLUS there is apparent damage to the threads of the captured nut, as well. The factory manual for my 89 Olds 88 does not address re-using of these bolts.

Please, only answers that are factory or dealership-verified unless you have metalurgical &/or engineering knowledge to share - I can easily come up with 'conspiracy theories' on my own & I have a friend who gladly supplies me with 'just re-use it with a bunch of loctite, don't sweat the same stuff' advice whenever he gets the chance.

FYI, for all of you who have ever broken torx bit bits or destroyed the female socket in these damn bolts, here's THE tool to take them out.

http://www.etoolcart.com/gmseatbeltboltremovaltool.aspx

Thanks, in advance.

Later,

GeoD