Audrey's 1965 Barracuda project

Started to work on the fenders today, both need some repair in the low part behind the wheel. Fender are from a 65 Valiant, not the originals. Then I'm gonna sandblast the inside and paint. When you mount the fenders, should there be anything in between the fender and the body? Like seam sealer or a gasket or so?

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seam sealer before install