The transmission was serviced only 3000 miles ago (right before I bought it). The fluid is clean, almost clear with a red tint. Level is correct.
I actually lucked into a nice transmission shop here in town right after I bought it. It wouldn't shift into passing gear (can you say putt-putt?!). The mechanic really liked the supras, and after driving it, didn't believe it was the transmission. He correctly identified the problem to be the throttle position sensor, and then also identified the strange noise in the rear to be the limited slip in need of a fluid change. And he told me I would need a new carrier bearing sometime soon. He said the tran fluid looked good too. At the time he serviced the car, I had not had any problems getting past 3rd gear. It was a couple of weeks later that the first incident happened. Then it was another 500 miles before the second incident! It acts like the O/D button has been hit, so next time I may try to turn it off and back on again.
The mechanic at the transmission place said a rebuild will run around $1800 (he was estimating on the high side).