How do you fix a 1993 Ford Thunderbird that won't go into overdrive?

Buy a new transmission or rebuild the transmission my cougar did the same thing and i drove it everywhere with no overdrive wich is a real gas guzzeling thing to do

Note added 7/5/2007: While replacing/rebuilding the transmission should fix the problem, I would get a second opinion. It may be fixed for a whole lot less money, if you are handy. I have fixed a number of transmission problems on my 1994 Thunderbird myself with shift kits, and replacing various solenoids, sensors and switches, etc.

Actually, theres a line that might be rusted over. A simple can of WD40 would do the trick lol. I had the same problem with mine we sprayed the line down works just fine in OD now.