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Description
Mishimoto 2017+ GMC 6.6L Duramax L5P Transmission Thermal Bypass Valve KitThe Allison transmission is the backbone of your L5P Duramax. It's responsible for transmitting large quantities of torque from your V8 diesel powerplant. This torque generates a lot of heat, and if that heat isn't dissipated, it can destroy your transmission. The transmission cooler does a good job of keeping trans fluid temperatures in check, but only if the fluid can reach it. The stock cooling system of the Allison 1000 transmission utilizes an in
The Allison transmission is the backbone of your L5P Duramax. It's responsible for transmitting large quantities of torque from your V8 diesel powerplant. This torque generates a lot of heat, and if that heat isn't dissipated, it can destroy your transmission. The transmission cooler does a good job of keeping trans fluid temperatures in check, but only if the fluid can reach it. The stock cooling system of the Allison 1000 transmission utilizes an in-line thermal bypass valve that controls fluid flow to the transmission cooler. The purpose of this valve is to prevent transmission fluid from flowing to the cooler until it reaches operating temperature. The thermostat inside this valve is prone to failure, however, and when that happens, the fluid never flows to the cooler, and the transmission can overheat. That's why Mishimoto has developed a full-flow thermal bypass valve upgrade for your 2017-2019 Chevrolet/GMC 6.6L Duramax. Our CNC-machined aluminum full-flow thermal bypass valve not only looks better than the stock unit, but it performs better too. This Mishimoto thermal bypass valve eliminates the internal thermostat, providing full fluid flow to the transmission cooler in all running conditions. This setup is ideal for owners in warm climates, those performing heavy towing, and trucks needing the best possible cooling efficiency for their transmission. The Mishimoto thermal bypass valve features strategically machined internal passages, providing improved flow over the stock valve for more effective cooling. In addition, cooling fins machined into the valve body adds even more heat dissipation. This 2017-2019 Chevrolet/GMC 6.6L Duramax L5P Full-Flow Thermal Bypass Valve Kit is built to last a lifetime with a durable black anodized finish and our Mishimoto Lifetime Warranty.This Part Fits:
| Year | Make | Model | Submodel |
|---|---|---|---|
| 2017-2019 | Chevrolet | Silverado 2500 HD | High Country |
| 2017-2019 | Chevrolet | Silverado 2500 HD | LT |
| 2017-2019 | Chevrolet | Silverado 2500 HD | LTZ |
| 2017-2019 | Chevrolet | Silverado 2500 HD | WT |
| 2017-2019 | Chevrolet | Silverado 3500 HD | High Country |
| 2017-2019 | Chevrolet | Silverado 3500 HD | LT |
| 2017-2019 | Chevrolet | Silverado 3500 HD | LTZ |
| 2017-2019 | Chevrolet | Silverado 3500 HD | WT |
| 2017-2019 | GMC | Sierra 2500 HD | Base |
| 2017-2019 | GMC | Sierra 2500 HD | Denali |
| 2017-2019 | GMC | Sierra 2500 HD | SLE |
| 2017-2019 | GMC | Sierra 2500 HD | SLT |
| 2017-2019 | GMC | Sierra 3500 HD | Base |
| 2017-2019 | GMC | Sierra 3500 HD | Denali |
| 2017-2019 | GMC | Sierra 3500 HD | SLE |
| 2017-2019 | GMC | Sierra 3500 HD | SLT |
Shipping Notes
- Free Standard Shipping on $100+ Orders to the USA.
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- Delivery to the USA:
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Exchange/Return Notes
- We offer a 30-day return/exchange service after receiving.
- Final sale items are not eligible for returns or exchanges.
- To process your return/exchange, please contact us at [email protected]
- Please click here for more details>>> Return & Exchange Policy
4.2 ★★★★★
Based on 17 reviews
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Product Reviews
★★★★★ 5
Comfortable, Simple, Reliable
Size: Tenkeyless, Pattern Name: Keyboard, Size: Tenkeyless, Pattern Name: Keyboard
This is a phenomenal product, and exactly what I wanted. I used to have wrist pain while gaming; I bought this, and then completely forgot that I used to get wrist pain while gaming.
The foam is firm, but comfortable; it’s very supportive, but also flat and consistent. It’s cool, so my wrist never gets sweaty or hot just from using the wrist rest. Its rubberized bottom prevents it from moving at all while gaming. I’ve used it for about a year, and the foam has no indentation at all; in fact, there’s not noticeable wear of any kind.
My one complaint, that I’ve seen in other reviews as well, is that the fabric skin of the wrist rest isn’t quite fit over the foam: there’s some extra material, and it can wrinkle slightly.
Overall, I’m quite satisfied with the product! It’s completely eliminated my wrist pain, and I’ve gotten a year of use out of it with no problems so far. I’d say that’s more than worth the fair price, and I would buy it again without hesitation!
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Reviewed in the United States on April 17, 2026
★★★★★ 5
Very High Quality Memory Gel Foam
Size: Mouse, Pattern Name: Mouse
Firmness is pretty solid, this material is high quality. This isn't that kind of foam that will start loosing it's shape after a year or two, this is a firm gel like substance and it's pretty comfortable.
The color is black as I expected, it's shape is rectangle just like in the pictures, it's appearance is as described.
The only think is that they do use a polyester cover, which does appear as though it may wrinkle over time, and it will likely not outlast the Gel Foam inside. Like I said though the Gel Foam is legit Gel Foam, I have heard these claims before only to find out that it's something far cheaper, that's not this.
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Reviewed in the United States on April 2, 2026
★★★★★ 5
Awesome
Size: Full Size, Pattern Name: Keyboard, Size: Full Size, Pattern Name: Keyboard
If you spend more than a few hours a day at your keyboard, stop what you’re doing and buy this wrist rest immediately. I was starting to feel serious strain after long typing sessions, and this simple accessory has completely eliminated the discomfort. It’s a true game changer for desk ergonomics.
The material quality is phenomenal. The memory foam (or gel) is perfectly supportive—it’s soft enough to cushion my wrists but firm enough that it doesn't flatten out or lose its shape, even after weeks of heavy use. The non-slip base is also fantastic, keeping it anchored exactly where I need it, no matter how intense my typing or gaming gets.
What I appreciate most is the immediate relief. The height and angle are spot on, positioning my hands and wrists in a neutral, comfortable alignment. The reduction in pressure on my carpal tunnel area was noticeable within minutes. I can now work for extended periods without the usual aches or stiffness.
This is a simple, high-impact product that vastly improves quality of life at the computer. It’s durable, comfortable, and absolutely essential for wrist health. Worth every penny for the long-term comfort it provides!
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Reviewed in the United States on November 7, 2025
★★★★★ 4
Pair with HyperX Keyboard Rest to complete the look!
Size: Mouse, Pattern Name: Mouse
Soft, comfortable, doesn't slide around, even on my XL mouse pad. Cool to touch which is nice.
After a year of use, fabric on top becomes slightly loose and bunches up when moving wrist around.
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Reviewed in the United States on February 18, 2026
★★★★★ 5
Well worth it
Size: Full Size, Pattern Name: Keyboard
Very comfortable and robust. This definitely looks and feels like a premium item. I had bought a few alternatives that were cheaper and they fell apart quickly. This one seems to have pretty resilient stitching and the fabric doesn’t bunch up which could cause a tear. The base has a non slip texture so it’s not going anywhere without some force. The cooling feel is a nice touch too.
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Reviewed in the United States on April 22, 2026