ATP TF-174 GM 4L80E Transmission Filter and Gasket Kit

This is the ATP TF-174 service kit for the GM 4L80E (THM4L80E, RPO MT1): the pickup filter that bolts to the valve body plus the pan gasket you need to close it back up. ATP builds it to OE dimensions to replace the factory filter in 1997-2000 4L80E units, so it drops into the same spot the original came out of with no trimming or guesswork.

The 4L80E is the heavy-duty automatic behind GM big-blocks and diesels: 3/4 and 1-ton pickups, Suburbans, box vans and cutaways, and the Hummer H1. On the bench or under the truck the job is straightforward once the pan is off. Break the pan loose and let it drain, pull the old filter straight down off the valve body pickup, seat the new filter with its neck seal, lay the gasket dry, and run the pan bolts up in a crisscross to spec. Refill with Dexron-VI and check level hot.

Run a fresh filter and gasket every time you service the fluid, and change the fluid before it burns if the truck tows or plows. One note from the bench: this gasket runs a touch thinner than the factory piece, so wire-brush the pan bolt threads and the pan flange clean before you reassemble, otherwise crud on the threads keeps the bolts from pulling the pan down evenly and you get a slow seep. No RTV needed when the surfaces are clean.