Ford Transmission and external magnefine filter

387K miles? Wow! That's rare for the 2003 model tranny. I have one too.

The Magnefine in line filter was installed after Ford paid for some kind of transmission work--probably a warranty claim. And they also spec. the use of the filter whenever a OEM rebuilt 4R100 is installed.

I finally bought my fifth wheel trailer, and am preparing my 2003 F250 for towing. I've bought 20 quarts of ATF, a TruCool auxiliary cooler and a new in pan filter.

Keep the filter and change it religiously every 20K or so.