John I have promoted Hayes tanks on RCU before and gotten nothing but grief from the three line guys, really good to get some support. I use exclusively 2 lines with either a Dubro or Sullivan filler in the fuel line between the tank and the carb. Get very neat cowl installations by mounting the filler inside the cowl on the firewall and a small hole in the cowl to get to the filler with the filler probe. I throw away any tank with brass tubes and a bung. Have had to use a Graupner tank a few times but try to make a Hayes fit if at all possible. Even when the brass tube tanks don't leak they don't seem to be air tight, engines always seem to run better with a Hayes. I am sure that will get alot of howls!