Found these being used in Europe to make a stainless steel, insulated bottom draining mashtun. Come in various sizes but most interesting to me is a 70L (appr 18.5 gallon with a threaded drain already installed or a 80L (appr 21 gal), but no preinstalled drain (see link below on the mods to add bottom drain).
As my plastic igloo is on its last legs (never could get it to stop leaking completely) and had a gusher doing a 10 gal batch yesterday, this might be my "upgrade" Price is around $150 but shipping to the US is an issue and probably expensive. These are for sale on several european homebrew shops' websites.
The are about 18" inside and I'll just order a peice of SS preforated sheet and cut my own false bottom. I think it'll make a stronger more leak resistant tun. I was contemplating a Blichman 15g or a Stout 19g with bottom drain, but either way those options are $400-$500 and are not insulated. I'll weld in the drain and use Kal's o-ring and washers to seal any other fittings in.
Here is the ebay ad...
Here is a 3 page write up on how to add a bottom drain and a false bottom to to it...
Anybody seen one in person or know where to get one state side?