I have a 91 ford f-150 xlt Lariat 2 wheel drive. I believe that I have an R4OD transmission. The tranny is slipping real bad and shuttering. The tranny fluid is brown so I assume it is burnt. I had the filter and fluid changed and that did not help at all. I have called around to find a replacement and I do not like what I am hearing. First off the tranny for a used one is $1200 for a used and $1800 to rebuild my tranny and get some warranty. The second item that concerns me is that I hear this transmission is a piece of junk. I was wondering if there is a different tranny that I coulr stick in there as a replacement or with little modification. Can anyone help me?

Im from mid-Illinois and when I need a tranny, engine, anything like that for a car/truck/van or what-ever, I usually go down to St. Louis where there is a place called "U-wrench it". I can go in, walk around amungst the vehicles, and bring in my tools (though limited by not allowing jacks or torches etc.) and pull pretty much any part I want. They are very reasonable on prices (I think I paid $75 for a tranny for a Bronco II once) If there is any such salvage yard in your area, you might give it a try

try a botel of Lucas Transmission Fix
Lucas Transmission Fix is a non-solvent formulas that stops slip, hesitation and rough shifting in worn transmissions and completely eliminates most seal leaks. Use in any transmission for preventative maintenance.Use also in light duty manual transmissions to increase shifting ease and transmission life.

Key Benefits
Contains no solvents
Lowers operating temperatures and stops foaming
Can be added to existing fluid without draining any out
Effective in an extremely high percentage of cases

drive it for a coupe days and should get better

There is 2 different trans used E4OD,,,,AODE....E4OD would be more $$$$
seen used ones for as little as $450.00 +shipping,,,,if you are handy enough
to install