i really like to use a lock washer on all my exhaust apps. on my header i use a plain washer, then a lock washer, then a standard nut and things stay nice and tight. a stover nut would work well too.

'79 sport 4x4 longbed <img src="/forums/images/graemlins/smile.gif" alt="" />
20/22R hybrid with EB's OS valves, 268c cam, offy intake, weber 32/36, thorley header, 5 speed swap, 34" LTBs, downey 3" springs, marlin hysteer, 4.88s and locked

'91 4x4 shortbed
22R-E, W56, the dd!