This is a nice story :-) Lucky you are that you might drive your van outside the "winter areas" so enjoy the Win for a long time. Mine starts to be a little bit rusty by using a lot of salt on our ways during winter time :-(
I'm going to rebuilt my 2000 Windstar's AX4S trans due to Overdrive band slippage. I took the OD servo out of the trans and welded the piston to enlarge it by 5mm. It works now, but better to place overhaul kit on it. Did you make some special operations when rebuilding? Using some bore kits, Accumulator overhaul kits etc?
Thanks for your hints, my brother just finished his Volvo's S80 Aisin Werner AW5550 tranny and there was quite a lot of stuff to proceed using CNC machine.