Steel floor pan plugs

Does anyone know a source for those steel plugs that have the tabs you push down to lock in place and then pack full of body sealer? The ones in the inside rear quarter of my GLHS have rotted to nothingness.

I was wondering how the heck the RR quarter panel got all that mud on the inside . . .

I used a piece of sheet steel cut to size and a couple pop rivets. Everything went together wet with JB weld and lots of undercoating on the outside after the epoxy setup. The repairs I did a few years ago on the Shadow are holding up very well.