External Transmission Control Filter

This one’s easy….. Allison requires it at 5000 miles. Then you’re off the hook until many miles later. (50,000/24M). Here it is:

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You’ll find it on the bottom of the transmission, can’t miss it. There’s a magnet there…. clean and place on new filter! You’ll need a little Allison Fleetrite Synthetic ATF to top it off again when you’re done. I bought a gallon, some people bring a small container and schmooze the shop out of a few ounces out of the bulk barrel. By all means, read the Allison book that came with your coach, or download from the web…


The book mentions another filter, the auxiliary lube filter. The best I can tell it is NOT installed on the 2500MH.