I didn't trust the no gasket or RTV routine with mine (either set, I have one on my 23 and ran them on my 27 for years) so I put regular header gaskets in there. However, on Dans 455 Olds he just bolted them up with no gaskets so far and through a lot of hours test running the engine there have been no leaks we can see.

But I plan on installing gaskets when I put the ones back on my 27, just because I am old fashioned, I guess.

Don