Maybe I watched "Two Lane Blacktop" too many times, but I always wanted something with a 4-speed, and I figured this was my chance! The tranny is a '68 Mustang small block TopLoader 4-speed. It is cast-iron and is virtually a direct swap for the 3-on-the-tree cast-iron TopLoader that was stock, other than:
(1) shortening the driveshaft due to the 4-speed's longer tailshaft
(2) installing a DKT (David Kee TopLoaders) tail housing for several different shifter mounting choices
(3) rerouting the speedo cable to the passenger's side and installing the proper speedo cable gear of opposite tooth angle
(4) mounting a microswitch on the reverse arm and lengthening the wiring to it for the reverse backup lights.
I purchased the trans locally out of Craigslist for I believe around $500, and I installed a CenterForce clutch and pressure plate.
The shifter is a stock '66 Mustang unit that I purchased at the same time as the trans. I had to put the stick in my shop press and straighten it out quite a bit so it would clear my bench in reverse, 2nd, and 4th. Also in order for the shifter to be far enough forward to clear the bench, it is mounted in the middle set of holes on the DKT tailhousing, and I simply shortened the shifter rods and welded them back together. The Mustang shift boot and trim bezel make it look factory, the reverse lockout still works perfectly, and I topped it off with a white shift knob with the shift pattern on it.
The only bummer about this setup is that with 3.70 rear gears and a 1:1 4th gear, she's humming about 3,500 RPM at 70 MPH. Some 3.23-ish gears would be a little happier for cruising; something I may do if I ever decide to open up the rear end to install a locker.