Last summer I was given an old anhydrous ammonia tank, same as shown in the picture.

The laws changed, these older tanks are pressure tested to something like 200 psi and the new regs require 300 psi. So for those willing to do the leg work theres some scrap to be had, and the best part is that most are on trailers that you can tow.

I haven't picked mine up yet so I cant tell you how much they weigh, the one I have they removed it from the trailer. If you have to cut the tank open anhydrous ammonia is an inert gas. But I would still advise you to look up the MSDS sheet.