Do you have to weld all the way along the plates against the underside of the floor or can you weld spots and then use a filler or something to fill in and smooth the look out?
We don't weld them solid to the floor pan. Its a filler plate, it simply fills in the area between the connector and the floor. No need to be a solid weld. We burn them in where its easy to, then use a good quality flexible seam sealer to dress it up. Its just cosmetic, its not structural in any way. I dont use body filler, as it can crack, or break, plus its a real pain if you need to remove it. On the bottom where it fits to the tube connector, I put plug weld holes, so you can get a good clean look. Sure you have to grind a bit off the top of the weld, depends on your welding abilities, some guys can spin a nice plug weld in there and you can not tell its even there.
I sell then for $39.00 for the 4 of them.
The nice thing about them is its easy to put them in, you can take it and grind a spot, fit it up, maybe grind another spot, fit it up.
I dont care what anyone says, I have never seen 2 cars identical underneath, especially the floors.