Found transmission fluid in radioator of my ford sports trac and trans is not shifting?

Replaced radiator and found trans fluid in it well after I have been driving it and now it won't move at all should I have to replace transmission or?

Your tranny is leaking fluid form somewhere. I have no idea how tranny fluid got into the cooling system. You do not have to necessarily replace your transmission. If you can patch the leak, then refill the fluid and you will probably be fine.

If Nikola doesn't know how trans fluid ended up in the radiator, then he shouldn't be offering auto repair advice. The transmission cooler is located INSIDE the radiator. When it deteriorates, the transmission pumps fluid into the coolant. When you shut off the engine and the trans fluid is no longer pressurized, the cooling system pressure forces coolant back into the transmission.

Chances are the transmission is now toast.

The automatic transmission has a fluid cooler built into the driver's side of the radiator, from the factory. The tubing inside the radiator must have rusted thru.