Sorry forgot to mention my car is a 69 and uses 4 sheetmetal screws with large fender washers.Thanks for your help guys...I mean the steel two piece plate that bolts to the floor.
The holes are pretty big so I assume it was some some of bolt/washer combo from the factory.
Here's a link to a repro piece...
Man, chasing down the various bolts and fasteners you need is annoying! LOL