i feel your pain...bed panels for any of the trucks aside from a stepside is impossible to find...Im in need of 3 of the 4 flat panels in front of and behind the wheelwells on my styleside longbox....side panels, let alone patch panels for a bed I have yet to see...
As to the VIN, on 61-6 trucks, the vin is on the frame, RH rail on the top surface in front of the front crossmember and behind the core support mounting area...would be about parallel with the generator or alternator as viewed from the side. The VIN on the frame is boxed on either end of the frame by a large star....On a unibody..61-3...the tag would be on the glove box door inside....as to the VIN itself....anything other then an F10 or F25 for 1/2 or 3/4 ton trucks respectively is a factory 4WD....usually an F11 or F26....

Keep us posted....if your uni is solid in the wall that splits the box from the cab then you got a good start as from what I have seen, they go away on the outside areas first.


Keep Us posted on what you find


-cs65