Special use permit SP6498 indicates that the tank is constructed of an alloy which historically has come to be associated with tank neck cracks. The cracks are detected visually or with an eddy current tester commonly seen in dive shops these days. There are numerous shop bulletins on the subject of old aluminum tanks of this type. It is usually recommended that they be junked. Not implying that the tank is defective, just make sure the required visuals are conducted every six months if possible. Actually, since hydro testing is suspected of causing the problems, your old tank may still be sound. (It seems to have been tested only once in subsequent years).
In fact, the tank has an original hydro of 10/72 and coincidentally is a 72 cu ft tank. This tank is one of the very first aluminum mods off the production line. The 72's were produced for a couple years until it became apparent that the 80's had a wider market.
