What would cause car (automatic) to not shift gears unless in OVERDRIVE ..?

I'm interested in buying this car it's a 1992 3000gt ..



Here is the ad - http://orangecounty.craigslist.org/cto/1



Anyway so they say that the car won't change gears unless overdrive is on.. Why is that..?



What kind of problems could this mean and how much $$ would it cost to fix them..? The price of the car is pretty cheap and I am wondering if the seller knows something that I do not..What would cause car (automatic) to not shift gears unless in OVERDRIVE ..?
Ditch that and look for another 3000 GTWhat would cause car (automatic) to not shift gears unless in OVERDRIVE ..?
it means you dont want that car-$2000 minimum to fix
sometimes changing the transmission and filter can fix that, but no guarantee.