I know the older C-4's use Type F, but at some point in the late 70's Ford started using Dex II. The 1980 Owner's Manual recommends Dex II. I am told Type F would provide crisper shifts. I think Dex II is now Dex 6 and supposedly backward compatible. I have both Type F and Dex-Merc in stock. I think Dex-Merc is closest to what the owner's manual suggests. See attached.
What are you all using in your C-4's, specifically if you have a 1980 version? What is the scuttlebutt on pros and cons of both fluids? I have no history on this tranny, in fact I don't know if it has been rebuilt at some point in the past, or if it even works.
What would you do if it was yours? Last year I drained the old fluid, cleaned the pan, and installed a new filter. By next year I plan to run and hopefully drive it so I want to be prepared with and use the correct fluid.