I don't have any seats to measure but I do have some of the "keyhole" plates that are mounted into the floor. The seat base slides into these and then is tightened down with a wing nut. SCARY!! The large hole is 1-1/8" diameter and the slot is 5/16".

"I always win." Working mainly alone I do not let my trucks win a war. Maybe a battle here and there but never the war.

Robert
55.1 GMC 450 COE
51ish GMC Suburban