Got a second healer ring from a Promethium lockbox, but this time from my hero healer (with a Combat Rating of 69) while doing FOS 2. It has an item level of 70 and has 27 resto, 9 resto less than the item level 78 version. Has a socket affinity of 13 precision. If modded with a resto III mod, the ring will give 56 resto in all. Not bad!
Edit: Managed to get my 3rd healer ring, this one identical to the first, while doing CC bounties today.. Also bought the T3 healer boots. Now all I need are T3 healer head, hands and waist to complete the set.
Edit 2: Got a 4th healer ring on my hero alt again, but this time it was still item level 70 instead of 78 even though my hero's CR was at 70. Weird. Don't tell me the CR of the gear you have equipped at the moment you open the lockbox determines the quality of loot you get?
Edit 3: Got a tank neck with a chance for 2 crit procs from a lockbox. Bought T3 healer hands too.