Transmission Service Kits

Doc's Diesel Transmission Service Kits

The Cheapest Insurance a Gearbox Can Get.

Nobody budgets for a transmission. It's the most expensive component in your truck after the engine itself, and the difference between a diesel automatic that shifts crisp at 300,000 miles and one that grenades at 150,000 usually comes down to one boring habit: fluid and filter service, done on time. Doc's Diesel Transmission Service Kits make that habit easy—each kit pairs a complete transmission filter kit with the correct ATF, in the correct amount, for your exact truck. Fresh fluid keeps shifts smooth and temperatures down; a fresh filter keeps debris away from the torque converter and fluid pump. One box, one afternoon under the truck, and the hardest-working gearbox in your driveway is protected for another interval.

Everything for the Service. Nothing to Chase Down.

Each kit includes a transmission filter kit—premium filter media, filter pan, and gasket—plus two gallons of ATF+4 fluid to refill the system after the drain. The gaskets are made from premium NBR rubber with fitted screw holes, so reinstallation lines up the first time instead of the fifth. No cross-referencing filter numbers against fluid specs, no discovering mid-job that you're a quart short: the kit is matched to your transmission, like our 68RFE kits for 2007.5-2024 RAM 6.7L Cummins 2500/3500 trucks. Doc's tip for a more complete service: leave the filters out of the transmission a little longer during the drain—the extra time lets more of the old fluid make its way out.

Built to OEM Specs. Backed by the Doc's Fitment Guarantee.

Everything in these kits is engineered to meet or exceed OEM design, fit, and function—the filter media, the gasket seal, and fluid that protects against wear, foaming, and oxidation in both high and low temperatures. A transmission is not the place to gamble on no-name parts, and with Doc's you don't have to. Our Fitment Guarantee backs every kit: if it doesn't fit your truck, we'll make it right. No guesswork. No BS.

Doc's Makes It Easy to Stay Ahead of the Interval.

Use our Vehicle Selection Tool—enter your year, make, and model, and we'll show you the exact service kit matched to your transmission. Then mark the calendar: plan on servicing your transmission filter every 25,000 to 50,000 miles, or 60,000 miles maximum. And here's the part most owners miss—OEM intervals assume regular driving, not hauling. If your truck tows or carries heavy loads, Doc's recommends servicing earlier than the book says. Heat is what kills transmissions, and worked trucks make more of it.

Free Shipping on All U.S. Orders $99+

A transmission service kit costs a fraction of one shop visit—and a rounding error next to a rebuild. Grab the kit matched to your truck, add a bottle of transmission treatment or your next filter set to the order, and everything over $99 ships free anywhere in the U.S. Smooth shifts aren't luck. They're maintenance—and Doc's puts it all in one box.