Are seat belt bolt holes threaded?

[esscoe]

I have a 1970 Euro spec 280SL.  I ordered some replacement seat belts, and when to remove the old inside seat belts by loosening the bolts on the trans tunnel, when I heard something "drop".  That made me think that their was a bolt nut on the inside of the the tunnel, in lieu of a threaded boss in the body pan itself.

I can't get access to this area, and the bolts no longer seem to anchor in here, confirming my suspicion that my seat belt bolts are no longer bolted in.  The outer seat belts do have a threaded boss in to the body pan, and threaded fine.

Does anyone have any experience with installing seat belt bolts to the inner trans tunnel side of your interior?  I have never seen someone use a bolt within a trans tunnel you can not access, it doesn't seem to make sense, and it could work loose, as opposed to a threaded boss in the body.  So If I'm missing something, any enlightenment would be appreciated.

Scott B
1970 280SL
1965 356 C Cab

[66andBlue]

Hello Scott, welcome to the group!
You are correct the bolts are screwed into fixed nuts in the tunnel.  Make sure that your old belts actually used these existing nuts and that no new holes were drilled.  The attached photo should give an idea where they are located.  You might be able to retrieve the loose nuts in the tunnel through the opening for the shifter.
I leave it to others to comment on a possible repair job, that is, re-threading, or helicoil, or whatever.