P0894 Code

[Lowcountry]

Ok, don't slay me but I debated whether to put this question here or in Technical section. I recently picked up a 2005 GMS Safari cargo with 148,600 miles on it. Rebuilt transmission installed 2 1/2 years and ~16,000 miles ago. Nothing leaking underneath (other than oil cooler line) and fluid looked good. Test drive was fine. Of course, after cash exchanged hands and 39 miles into the trip home SES light comes on. Van shifted fine through all gears during trip and I didn't feel any slipping at any point. Never even downshifted climbing the pass on the way home - acted like it was on level ground. Checked the code the next day and it's P0894. URG! It's been cleared twice and it came back the first time but not yet the second time with local drives. I have to admit that this van shifts as well or better than my '02 F250 7.3. Occasionally from a stand still maybe a very slight lurch but smooth all the way up through the gears, and rolling stops from 1st to 2nd are silky as are the rest. First shop said it needed a complete rebuild at $2875 due to torque converter slipping and running at 212. I have an appointment at another shop later this week to get their take. Thoughts in the meantime?

[Lowcountry]

Second shop went over vehicle. Per transmission, code never popped up during their drive and evaluation nor was it stored like O2 sensor notification. They felt transmission fluid was maybe darker than normal and suggested a drain and fill. Anyone have any thoughts? Thanks.