ccain529,
I have thought
of using the spray on box liner stuff, but I was concerned about adding thickness to the pan.
The underside is one thing, as nothing gets bolted to it, but inside you have break lines, e-brake, shifters, inspection plates, peddle assemblies, seat tracks, and a hose of other stuff that attaches to the pan.
Every hole, bend tab, seating surface, etc... would have to be cleaned in order for things to fit properly.
Doug