The trunk pan in my car is bad between the frame rails were water layed over the years from the trunk leaking. I only want to replace the metal that is bad between the rails. The other trunk floor metal is fine. Is it considered exceptable to only replace bad metal. Thanks for your help.

By the time you finish off the seams where you splice it in you might as well put the whole pan in. Not really going to save much time splicing it.

I did one like that a few months back, the rest of the pan was solid and this way I could save the factory spot welds. I'd say the time I saved not drilling out all the spot welds for one from the old floor alone made it worth doing it this way. Then you have to drill tons of holes in the new floor when you replace the whole thing... looking at big picture, it definitely saved me time and I prefer to keep as much original metal as possible.

I think the extra effort is worth it.

friend of mine did just that on a Daytona project they have in .

A lot of carefull trimming and trial fitting ,yielded a new pan that no one can tell was ever replaced.
He split it and rewelded it right down the lip pf the frame rail edge. Once ground down you can not tell for the top or bottom.

Plus they didn't have to remove the tail light panel to do it this way.