You should have changed out your trans, t-case and diffs at 30,000 miles.
When you overheat your tans, not only can you ruin the properties of the fluid, but as you pass approximately 265° you permanently alter the pliability of the internal seals. This will lead to losses in holding pressures that will allow bands and clutches to slip causing more heat buildup.
I've installed trans temp senders in a few of my automatic trans 4x4s and have noticed that when the temps get higher than I would like, the fastest way to cool the trans is to actually shut the engine off and wait. I thought that letting the cooling system handle it, like you did, would be the best, but I surmise that the combination of a 210 degree minimum coolant temp and the continued shearing of the fluid in the torque converter was the reason it was less effective.
I would also recommend getting a PML deep finned trans pan to aid in cooling.
http://www.yourcovers.com/transpan_11044.php