Update: I had another mechanic who came highly recommended take a look at the car. He went over to the original garage with the intent of driving it back to his shop, but it wouldn't move AT ALL. So he did an initial analysis and says there is a 95% likelihood that the transmission needs to be replaced. He offered three options:
1) Install a used transmission, which will likely have high mileage. Cost would be $1,500-1,600 plus $793 labor = $2,393. This is basically the same service offered by the service center at the dealership for slightly less money. This seems like a terrible option given the risk involved.
2) Install a re-manufactured transmission from Jasper which would be god quality, come with a 3 year/100K warranty. This would require the installation of an auxiliary cooler. Parts would be $2,813.75 + $882 labor + tax, etc.= $4,125. Expensive, but this seems like a good option given the warranty. Though pricey, this option would prevent the premature scrapping of an otherwise good van -isn't that better from an environmental perspective, and thus more Mustachian?
3) Install a rebuilt transmission with a 2 year/24K warranty for $2,300 parts + labor, taxes, etc. = $3,470
He mentioned scrap value would be very minimal (i.e. $250-500).
Somebody punch me.