Seatbelt mounting Spit 1500

[wimpus]

Hi all, 

 

Could be that I need to replace one of the seatbelt mounts at the sills on my car, need to replace sills and floor edge around the mount isnt nice.

 

Does anyone know what threads they are ? 

Can't find it anywhere.

 

Want to make my own as all the plates you can buy have the hole /mounting in the center of the plate.

 

On my Spitfire its more at the side of the plate, so want it to look original.

[NonMember]

I think they're 7/16" UNF. It's interesting that yours is offset on the plate - all the ones I've seen have been pretty central, including those that look unmolested and original.