Forgot to mention the TVC. On the TB end, it seems to be adjusted properly (that was the FIRST thing I checked). I'm wondering if perhaps there is a problem with the TV link inside the tranny.
The other day, I had a tranny cooler hose come apart and it shifted smooth from 1-2 at ~12mph (shortly after the hose came off the aftermarket cooler, but before I stopped moving)
[I had bought this truck 4 days prior]
Tomorrow I guess I'll drop the pan and have a look. I'll be flushing the old ATF out of the cooler lines when I reassemble (it's nearly black).
No PDF documents or book recommendations? I haven't found much technical literature.
(similar, but not a 700r4) 4l60E Rebuild
Edit: decent page 700r4 tech info
Edit #2: pictorial GM 700R4 Transmission Upgrade Shift Kit