transmission help...please (a bit long)

[Amy Soich <casoich@domain.elided>]

A little tranny history to help diagnose:

 I have a 1978 International Scout II. The transmission was fine until my
scout died due to wiring problems last february. It sat for 2 months and then
was towed to a shop. It sat there for an additional 6 weeks while they looked
for the wiring prob. Wiring fixed, went to pick it up and it wouldn't go into
drive, reverse..nothing. they said it might just be low on tranny fluid. They
put in some sealer and fluid and it seemed to fix it for the time. I have
always had a tranny leak, but it was worse than ever now. I had to put tranny
fluid in it every few days.  I never let it get low though.

 Now..the tranny had been slipping occaisionally but the other day something
must have happened. It will go into drive and reverse and everything fine,
however it won't shift out of second gear. My husband said he was driving it
home, it was ok and then at a red light..it just wouldn't shift all of a
sudden. He left it at my mom's house since he was close to there. He didn't
want to burn out the engine.

 The engine will be revving like hell but it's not shifting. It has a top
speed of 25 now and is not driveable. What happened? Why won't it shift
anymore? A friend of mine said "it sounds like you dropped a vacuum line" 
what does that mean? Could that be it?

 Any thoughts on this would be greatly appreciated because I know absolutely
nothing about transmissions. Please email me as I don't often check the list.

Thanks in advance,

Amy