RV LIFE Multisite Forum, Wander The West
Propane tank
I assume you need the ~5 gal. lay down style. I've heard you can get them re-certified, if they are out of date. However, if you are worried about the older valve, check here, near the bottom, "recent exclusion....":
http://www.damouth.com/RVStuff/OPD.shtml
The best price I could find was...