Yeah - your transmissions got problems
Anyway, you're going to need it rebuilt or replaced. 1600 for a 94 SL with a broken transmission and, I take it, needing a new front bumper (from your other thread)? I'd say thats a pretty fair deal barring as long as the rest of the body is good and the engine runs strong.
I don't know your location, but heres a few spots to look for
http://www.kormextrans.com (this is where a lot of 3000 owners get their transmissions)
http://www.asapmotors.com/Mitsubishi.html
http://www.usedengine.com/mitsubishi-engines.html
http://www.automatic-transmissions-rebuilt.com/
http://www.used-car-parts-locator.com/