My personal take is that it's not the gasket. It's the location. That joint sees the most cyclic stress/strain from the engine rocking.
Rather than focusing on the gasket, I recommend using decent locknuts. The type that has a little crown on top which is slightly coined/dimpled. Use them once.
Someone with first hand experience may chime in but that's where I would start. Good luck.
Hows the weather in Albuquerque? I'm a UNM alum. Lived there between '92 and '00. I miss Los Cuates and good green chile.
