1st Gen Rollbar threaded socket

[86Original]

Does anyone know what the threaded hole in the roll bar vertical tubes (typically covered by a plastic plug) are for on the 1st gen 4runners? It looks like it could be an anchor point for a shoulder strap, but I haven't seen any 1st gen 4Runners w/ shoulder straps in the back seat. Have you?

I've had this rig for 19.5 years and never have known what those holes were for.

 

[fourwd1]

It is for a shoulder strap. Never seen one equipped with it either.

It's an SAE bolt size, not metric. Something like 7/16 or 9/16, can't quite remember but I'm pretty sure it's a fine thread, not coarse.