Just FYI, you can get POR15 on Epay from
Eastwood, sometimes they have can & even full kits on sale at much less than most folks. The kit is a the best buy, the clean & prep chemicals are all there, & one small can of POR puts down a lot of coverage.
Simple prep work, and if you have any pinholes, or even screw holes you want to fill in just lay down a little fiberglass mat and paint over it like resin. Have known people to fix badly rusted floors that way too. Dries to a smooth glossy coat that is darned near bullet proof too.
I have it on my trans cover in the cab, diff cover, oil pan, and valve cover, and I'm planning on doing the whole interior under the dash & behind the seat/tank.