I picked up a dented center fill tank from Ebay for a good enough price to try my hand at separating the halves and fixing it. It came with a brass cap that made the purchase worth it all the more. I like to build up the dented down top with brass rod and a torch then pop it in the lathe to re-true it. Restore the knurled edge and polish. Also found a tap to chase the threads in the filler neck. Most of the time I bring these odd tools to Portland with me so if you need to use them just say the word then get your butt to Portland!