518 Screech in neutral

Thanks AJ, good info, and as often, a bit beyond my knowledge, but thanks for the logical assessment.
I am now recalling (best of my memory..) that I may have briefly heard something similar coming down from OD/lock-up cruise to near stop and switching (toggles) out of OD/lock-up when I forgot to do it earlier. So maybe something in the OD/lock-up system was complaining???

At any rate, I will start checking things when I can get back to it. Younger members of my extended family seem to have plans around, St. Patty's!