The answer to which vehicle that floor frame came off?
If you look at the pillar where the door hinges bolt on, There are 7 holes per side.
From the top,
Windscreen support bolt.
next two door HINGE bolt holes
Middle two FORD mirror mounting holes
Lower two bottom Hinge.
On the Chev cabs that I have seen pics of the Overtaking mirror is mounted onto top Hinge.
Of course they may be exceptions that I am not aware of.
Good luck in your search for 20" wheels. I would send you some but they would be a bit heavy for the postie!!!!!!
