I feel for you and felt in this “finger pointing game” as well when this trans left me stranded from the C D F drum shifting. Don’t pay for them to tear it down and rebuild which costs a ton. The 10 speeds are about $3500 over the counter to buy from Ford. I’d say just get a new trans and see if corporate and / or the dealer will help with that so all is new since there’s a lot in these transmissions that need to be fixed and the diagnosis and labor will get expensive fast. A new trans and a a few hours to replace it will be way cheaper and now you have a good truck. When the C D F drum in my trans failed, it also need a valve body, torque converter, main shaft and several other parts equaling around $6000.00.