I have a 2003 Mounty with the 4.6L V8, bacause i am pulling a trailer and do not have the towing package, I purchased an add-on transmission cooler. Well I dropped it off last night and the mechanic told me it already had a factory one on it!! He said it was between the radiator and the fan...is this true??? I am not very mechanical(obviously). SO i figure Ic an trust you guys more...any remarks?

It has one built into the radiator. If thats what he means? In that case the tranny fluid could actually be heated up from the coolant in the radiator. Adding another cooler(even if it has one and you have the extra in hand) isn't a bad idea at all. With all the power the 4.6 makes its definetly hard on the tranny. Get it installed :p