My truck originally had a 3 on the tree w/ overdrive, lever for it was under about where the key is. it was a seperate pull lever for the overdrive under the dash. can you still get these overdrive transmissions. It's since been converted to 3 on the floor. I've decided that a TKO is too much $$ but i certainly could use the overdrive. Could i put an overdrive unit on my 3 spd or do they make them for toploaders? I'd like to get a toploader soon and have someone to find me one cheap. Are these units worth it?

Thankls for the info
Nate