'94 F-150 103K miles. I have found transmission fluid in my radiator and realize the trans. cooler is leaking. My sources tell me that rarely does the coolant leak back into the transmission unless it is a very large leak. They are telling me that replacing the radiator is the best way to go due to age.I would like to hear from anyone with more info on this. Thanks, Emmett

 

I would replace the radiator for sure and I would also totally drain the transmission and replace tranny filter and refill the tranny with fresh fluid just to be on the safe side. If your torque converter has a drain plug I would also drain it as well, before you refill the tranny fluid.

 

Engine coolant can and does leak into the transmission.
The coolant will attack the bonding on the fibre plates and they will come apart.

Either replace the radiator or cap the cooler connections off and install an external cooler.

Change all of the the transmission fluid too.