More from the Internet - 3-Speed ID and Swap Info.
Q: Can I swap-over to an 833 4-speed and keep my current "3-on-the-tree" shift linkage, what other trannys can I use?
A: Well, we know that the early Chrysler A-903 & 745 non-syncrow 3-speeds are weak and and not much fun to drive so it is best to get a different tranny swapped into the car if you can afford it.
One option not yet discussed is to swap your 64 3-speed Dart over to the "tried & true" 904 automatic. This swap is really not all that hard if you have a "donor car" for all the parts, the conversion is pretty much a bolt-in deal, even the cutout for the pushbutton shifter is already in your 64's dash, under your current plastic manual shift plastic dash plate. If you want the automatic to be a column shifter, look for a 65 on the column linkage set-up, again a bolt-in swap.
OK, you say you want to stay with a manual transmission and the current "3 on the tree" column shifter. One swap I have done uses a later A-230 (70 & up) fully synchronized 3 speed. This is a much stronger gearbox and your current column shifter can be adapted to it by modifying the side cover levers and shift rods. (both need to be made longer) The downside to this swap is that the A-230 box has the later "slip-in" rear drive shaft yoke and speedo gear set-up. You would need a different drive shaft and a 66 speedo cable assembly to get this working in your 64 Dart.
(A fun point of interest, with some special machining to the reverse gear in an A-230, you can add a 4th syncrow stop ring to make a synchronized reverse gear!)
Now back to the 4 speed on the column idea, yes sir, done that one too. Used an early "flange type" A-833 and here again, did some creative linkage rod work, combined with some minor sheet metal floor / tranny hump "hammer work" to get a little more room for the rear 1st / 2nd shift rod & lever. Here is the crazy part of this swap, for reverse gear selection we made a special right-angle "operating lever" hooked to a short rod and "T"- handle, which came straight up through the floor next to the driver's seat! This worked but it was a bit scary seeing that you pushed the "T" handle *down* to get into reverse and pulled up to get out. Scary because there was no built-in linkage "interlock-safety" to prevent possible reverse engagement while in 3rd or 4th gear. If someone or something (like your fat butt) pushes that handle down while cruising down the road, it makes a nasty noise at best and lock-up or "Ka-boom" at worst.
In the end we found that the "4
on the tree" was not so great after all, just because the Mopar
column linkage is so weak and sloppy, you could never shift it real
fast. We later chopped-out the trans. tunnel and installed the Hurst
Comp. Plus floor shifter and life was much better.