http://www.tank-depot.com/dept/68/ A couple of things to think about when purchasing these tanks:
1. Ask for a completely sealed tank and get a fitting relocation kit
for each tank. This way you can customize it once you get it. It
worked out great for me plus you can get your hand in there to adjust stuff
just in case.
2. Measure you area at LEAST two times before ordering! I measured
twice and had Dave measure twice. Could be an expensive mistake.
3. Error on the side of too much weight if you've got the room. After
all, you don't have to load them all the way up.
4. Call them on the phone, don't order on the web to make sure you get
what you want.
Good luck!