I have my 67 plymouth Belvedere II (GTX clone) at a body shop here in New England and they have installed the rear quarter extensions with just a plastic gasket that doesn’t appear to be a great finish look and makes me nervous about leaks as well. I was under the assumption they are only installed with a seam sealer applied to the gap and wiped away them painted. Please help! I am paying a fortune for this and want it done exaaaaaaaactly right! Could anyone send some pics or tips on how theirs were installed??