While replacing the lower ball joints on this vehicle, I discovered that the transmission fill tube has rusted out and their is a rusted out hole on the top of the tube next to the exhaust down pipe located behind the passenger cylinder head.
I'll get a few pics later today after it stops raining. I've purchased a new tube but seek others opinions about how to replace this ? Could I drop the exhaust down pipe's and remove the shielding between the transmission and the exhaust pipe to get access. I understand that this filler/dip stick tube is also clamped on the transmission housing but can't confirm this as of yet.

 

I had this happen on my first Expedition (1997). I repaired it by taking a piece of heater hose and slitting it the long way. I filled it with RTV and then wrapped it around the tube where the hole was. I added a couple of hose clamps and gave it some time to dry and it never leaked again. You could try that and return the tube you bought...if you're so inclined.

 

To change the filler tubes refer to the appropriate attached PDF for whichever tranny you have.

 

Thank alloro. I was considering the same idea per a friends recommendation. The problem is where the hole in the filler tube is next to the exhaust down pipe of the exhaust manifold.
A potential solution is to use your technique with high temp silicon hose. Use the same process you outlined above while covering with a heat shield material similar to that used on the started motor wiring which runs down inside fender well and is passes near the exhaust down pipe down to the starter motor.