What all do I need to put a 4 speed in my 3 speed Duster besides the tranny

If your 3 spd is already on the floor, then you need:

Tranny, driveline yoke, shifter, shift rods, bellhousing, shift knob, shift boot and bezel...

If you have a 3 spd on the column, add a mig welder (you can use screws and body sealer, but when adjusting the linkage or installing the tranny I don't like getting my knuckles ripped up by the screw tips), sawzall or plasma cutter/torch, new tranny hump, possibly new carpeting...

-D.Idiot

Wow mine is already on the floor. So basically I need the whole assembly? Iguess I need to find a donor car?

DI is right in his list,

leaving out only the necessity to buy some cans of "patience". However well you plan the task you will be astounded at what you didn't forsee. This is one job I could do in a day or so now, having done it once, and the time now is because I like shiny clean, stainless bolts and washers, stainless locknuts,shiny tranny, and on and on. Getting the fasteners together makes time flow like a river. Clean and polish that tranny case, well heck, let's just open er up and see what we can see, oops, now I need the synchro fork seals to the case, where do I get them, hmmmm. Polish that input retainer,ooops now I need the gasket, and on and on. I think it is a lot of fun and I think Rob does too...but a donor...uhhh don't double your pleasure laying underneath removing before reinstalling. PM me, I have a complete spare set or two of all of it. and pics, because I wanted a hydro clutch, not a "Z bar".

rock
'64d100