The Owners Manual specs Mercon. Somewhere (Can't remember where) I read Mercon V . Truck is driven regularly, I pull a Steel Two horse slant load with living quarters regularly on a goose neck hitch. Also I get the TC shudder frequently. Fluid is changed every 20,000 to 25,000 . Have tow pack. and factory trans cooler. It is the 4R70W? tranny by the way.
Thanks for the help.

 

If it is a 4R70W, and I think it is, then MERCON V is the correct fluid. When the truck was built MERCON was, but Ford now recommends MERCON V for all 4R70W transmissions to prevent shudder.

 

Thanks! Can the two be mixed/ I.E. in a regular drain the pan and refill. Or does a complete change need to be made??

 

A very small amount of mix (like, less than .5 quarts) will not cause issue, but don't mix more than that. A complete change should be done if converting from one to another. There are several multi vehicle fluids out now that cover the specs for both fluids in one. Mobil 1, Pennzoil, and Valvoline all have them out. I think Mobil 1 runs about 6 bucks a quart at autozone, though I can't specifically remember.