They are mounted through the holes that are visible from the inside sheet metal. On the driver's side you can see the two holes that need to be drilled through the cowl. On the passenger's side, the glove box blocks the view.

1951 GMC 1 Ton Flatbed -- It is finally on the road and what a great time I have driving it!
1951 1 Ton Completed

My Chevy Master 4 Door is on the Road!