Looks like Asahi "spun steel" E12079 3500psi tank.... sold under other names such as Sherwood, Dolphin, etc..... made in Japan.
I'd check first to see, but I think the DOT exemption for them expired April 30th, 2006. But maybe I'm wrong and Asahi renewed their exemption on E12079 tanks. (I haven't kept up with them).
Here is the exemption, but the files seems to have been moved on DOT's website
http://hazmat.dot.gov/exemptions/E12079.pdf
EDIT: looks like the DOT renewed Asahi for these tanks until 2010. So you can still get the hydro'd. (I just remember that was a concern with these tanks a couple years ago).
see
http://hazmat.dot.gov/sp_app/special_permits/docs/12000/SP12079.pdf