I've got the "euro" looking mirrors on my 92 F150, the same ones that are power mirrors if you have that option. I don't like 'em. I want to put the towing style mirrors on there. The mount seems different. Mine is about 3 inches longer. I know I'll have to put some nut serts in the door, but is there a back plate that covers the holes in the top?

 

Don't be surprised if those towing mirrors cost you about 1/2 MPG at highway speeds. You're way better off with the aero mirrors and a set of the towing mirrors that slide over them for temporary use when needed.

 

IIRC, there is no backing plate, just the nuts in the door for the bolts to thread into.