The transmission "expert" claims its something he calls "binding/clamping"..

He says I either need a new tranny or an overhaul. Either way I am out $2000 or more.
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I am back to square one..
either I invest $2000 or so, in the van worth about $2000 or trade it in for a $1000 and get something different.

 

You can't get something better for $2000 can you?If it were mine and didn't want a car payment I would keep it.
Is this the only problem it's having?
If a new tranny will let it run for a few more years then it's worth rebuilding.
Make sure you go to more than one tranny shop for estimates.Some of the big chains just remove and replace transmissions from the shelf.These places are faster getting your car back to you but are more expensive.A local reputable shop can give you a better deal on a rebuild because they just replace the parts that are bad.I use a shop where the owner is so proud of his work he drags you into the back of the shop to show you all the parts he replaced.