I tried out a set of collector gaskets (I forgot who made them, duh...) made with a steel shell, and a high temp packing, wrapped around the perimeter of the hole, on my 71 C/10, and they're great. Haven't had a problem yet. I know Earl's makes the same type of gasket for the header-to-head, and I need to get a set of those. I've had more trouble blowing out #8's gasket than any other. I haven't had much problem after finding some lockwashers for the header bolts, but I'm still waiting... I've removed the collector gasket twice on the pass. side, to pull the header out for inspection of the flange, put it back with the same collector gasket, and it doesn't leak yet. Only downside, if there is any, is the price. Paid $25 for the pair, but seem to be well worth it, as they've been on the truck for 1 1/2 years, no problems. I swear by them now, put them on when I do custom exhausts for my friends (mandrel bent, cut/fit/weld systems). Darren