Hello- There is a 1997 Aerostar cargo van that I'm thinking of buying. It looks great and he's only asking $1600, but the seller mentioned this:
"Transmission has a tendency to shift to the low gear (but still runs). I was told that speed sensors on the trans and rear axle needs to be replaced (they send speed info to the computer that commands transmission when to shift gears)."

Is there any way that I can verify this using a scanner? Would a prepurchase inspection by a mechanic be able to tell if the transmission was on its way out or not?
I'd appreciate any guidance or advice that anyone can offer.