Grab a length of 6-32 all thread from Home Depot or similar. Cut it to an appropriate length and put a nut on each end. (a second jam nut can be a good idea if you don't have a/c grade locking nuts). Leaks? We don't worry about no stinkin' leaks. Just drill each end of the muffler very slightly bigger so the all-thread just barely goes in. A #27 (0.144 in)drill is a good close fit.