Here's one I made earlier. Not much help to you as I'm located in Australia. Tig welded 316 stainless. It cost me a small fortune (Approx $150!) to make as I bought 2 dome end caps, a Speedflow weld on fitting with cap, 4" dia pipe, a large conical reducer and a few billets which I machined for the split clamp and petcock valve boss. I broke the stock China tank stud fitting it up.