Can't help w/specific swap info other than to say you can replace the AT w/a similar year manual. Might be easiest to buy a whole junk Ranger w/manual tranny to get everything you need then scrap the rest.
But before you do all that, have you done the easy things first? Obviously fluid level, check the modulator for having ATF in the vacuum line or having a ruptured diaphragm or clogged orifice that keeps it from retracting the pin when vacuum is applied, check the vacuum line for splits or leaks- especially the rubber sections where they connect to the modulator and to the vacuum source.
Even the engine tune/condition can have an effect on this. If the vacuum is low the tranny will tend to hunt between gears.