taking the sawzall or cutoff wheel grinder is the first step. don't forget to slot or drill one hole a couple of drill sizes bigger. this will help a lot with sealing, as well as cracking that sometimes occurs at the head flange. i "stole" these ideas off of member Mr. Pbody many, many [and more manys] years ago, and these ideas will seal even the thinnest of flanges and prevent cracking. Thanks Mr. P !
