Seam sealer for wheel wells?

[Toro]

I'm replacing both wheel wells while doing rust repairs in the rear floor. Should some sort of seam sealer be used when installing the new wheel wells? I'm not sure if it was from the factory, but there appeared to be some kind of sealer residue left after the old ones were removed.., but then again it was hard to tell with the rust. Thanks!

[notsolo]

I used polyurethane caulk, don't have any seam sealer. This has worked for me for 30 + yrs. Primer then polyuretane caulk, seams gaps laps etc. 2 thin beads on mating surface, then after bolts are tight, gap on top. Paint 24hrs after that.