Looking at 83 240D tomorrow

[Ripple7]

Hi All,
I'm spending some time with a 83 240D (176K miles) tomorrow with a "bad" transmission and might buy it if the price is right. The body is solid- it's sat for approx a year- 6 months ago when I looked at it - it started right up. The reason for "bad" being in quotes I'm not certain the tranny is toast and I'm hoping for some insight. It's an auto- when you put it into any gear - you can feel the transmission move but it doesn't engage in any gear. Transmission fluid level is good and doesn't smell burnt. Could this be as simple as a vacuum issue? What about the engine sitting so long without running?
Thanks for your help!!