Mounting points for W123 Third Row seat shoulder belts?
 

I just installed a set of third row seats in my daughter's '85 300TD. Included were the seats, bottom tray, all fittings, hardware, belts, second row seatbacks with headrests, etc. What a job!

Anyway, the only SNAFU is finding the mounting points for the roof-mounted shoulder harnesses. Apparently caged nuts are waiting for me behind a curtain of pristine headliner and an inch of insulation—but where exactly? I don't want to remove the windows to drop the headliner, but don't want to guess wrong and make unnecessary holes trying to find those hidden caged nuts.

Can someone with either a 300TD with those belts (or someone with a non-third seat 300TD with its headliner out) please measure from specific reference points, such as how far above the window rubber trim, or how far back or ?? A few photos with explanations would be wonderful!

And if anyone else is trying to mount these seats in their 300TD, I do have some pointers I'd be happy to share, now that I've been through the crucible!

Thanks!
~ Dave 818-606-2097