Take a look here. http://www.impulse-owners.com/manual...ket_manual.pdf
Depending on the age, you could have a gas through or a vertical Max-Flow. Possibly a Shocker style Max-Flow too. Anyway, they bolt up into the body (either the gas trhough or the Vertical Adapter) with one allen head screw. There should be an o-ring there too that is at the base of the screw between the reg and the body. That ring is tight on the screw. That will give a little cushion and help to keep it from unscrewing.