where can i get an overdrive unit?

Sorry can't help there, be a case of trolling through some of the posts in these forums about what will fit, Thought I had seen something about 518's being overdrive,
Gear Vendors do a stand alone unit but it is long.

Research on GOOGLE. There's tons of information online. Or you can try this forum as well. Type your inquiry in the "search" box above, and you will get information.

drop down to page 2 of this line of threads, "1993 direct overdrive"
It is on 2WD but will give some idea of what model to look at.

thanks guys

You could Go with a new set of rearend gears, go up on your tire size, or if ya feel spunky, throw in a gear venders unit....
OR, just put in a auto with a overdrive. Wanna be crazy, put in the overdrive, and then put on oversize tires, then a 3200rpm spring.

Don't know the ettique of mentioning elsewhere to look but our baby brothers have some interesting parts in their classifieds

Remove your high idle screw, and install a 3200 spring. Gives a little more.

i have the 3200 rpm spring in it. top speed was about 75 with the stock spring haha. But what does removing your high idle screw do? is it alright to take that out?

I've always had my high idle screw in the glove box, won't hurt a thing. My truck used to top out around 85, now will do over 100mph with no idle screw and the 3200 spring. But I have overdrive. Removing the screw just lets the throttle travel farther.