So sorry to read about your transmission troubles Burbman! :( Glad you got it fixed though and were not stranded out in the boonies someplace.
Your post makes me wonder about my truck. I have 250,000 miles on it with the original stock transmission. I have maintained mine just about the same as you have, perhaps even a bit more (drain fluid and change filter every 12,000 miles, complete fluid change every third year which is about 36,000). I am wondering if perhaps I should just bite the bullet and get the trans replaced or rebuilt. Like you, it seems to be working fine but sure don't want to get stranded on my trip to Florida next month. You sure got me thinking!!
Barney