Mishimoto Transmission Cooler, Silver (MMTC-DMAX-17SL)
Fits 2017-2019 6.6L Duramax V8 (L5P)
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Price tracked 11 times since Jul 26, 2026 at the stores we check daily, not eBay: low $499.95, high $499.95, currently $499.95.
where to buy · 3 retailers tracked
A direct-fit replacement for the factory transmission cooler on the 2017-2019 L5P, built as a 13-row stacked-plate core to pull more heat out of the Allison's fluid.
why this one — Pick this over a bar-and-plate cooler if you want the easier install and a warranty you can actually use, since Mishimoto rates it an easy install and backs it with their lifetime warranty. Two honest catches: Silverado grilles need minor trimming to clear it, and Mishimoto publishes core volume and fin area gains but no measured temperature drop, so you are buying on spec sheet rather than test data.
Cooling part, no power claim applies. Mishimoto publishes 67% greater core volume and 164% greater fin surface area vs the OE cooler, 13-row stacked plate, core 27.95in x 5.78in x 1.25in. No measured temperature-drop figure is published for this SKU. source ↗
No published gain figure for this part, and nothing here is a guarantee. Price is a list price and can lag the retailer; confirm at checkout. See how we check a price and our affiliate disclosure.