I am using a Remflex gasket on my 261 that was rebuilt last year. So far, I've put about 1,000 miles on my truck, and it is sealed tight. I do have issues with the manifold stud/collector pipe connection coming loose, and having to snug it up periodically. Hopefully the Remflex is a good long term gasket, I've replaced manifold gaskets in the past on my old 216 and it was not fun.
