Chris--I gave up torch welding sheetmetal a long time ago. Yes, It is still a great method to do real Metal Body repair, but for the last 20 years or so I TIG weld and hammer exclusively. I really miss my little Marquette set, though. I have, still, my small Purox for Aluminum work, and a really neat little Victor YJ 40 set that I have never used, but don`t even do much Ally any more. There is a young fellow in Portland that I send all my Aluminum customers to. He learnt in the Bay area working on expensive aluminium European cars....I use my old Victor (medium sized) for all cutting, heating/shrinking with a 000 tip, mostly, and I have a Rosette that I have used about half a dozen times in the past 10 years....And Frank is right. Ideally if you take care of your equipment and use it properly, you can get by without check valves. But I would put them in, that`s for sure...