I was in the junkyard pulling parts for a rusty rear end job (brake lines, fuel tank straps, subframe, rocker panels) on my '99 CSVT and since I dropped the tank, I took the fuel filler neck to boot. The SVT filler neck is steel (rusty), and this older donor is all plastic. I don't know why they went to plastic, but now I have the option of replacing the steel filler tube with the older plastic one or treating the rust on the non-leaking steel one in place. Are they interchangeable? Should I grab that old tank too or is it compatible if I went to a plastic filler neck?