The Mishimoto transmission cooler for the 2003-2005 Chevrolet/GMC 6.6L Duramax LB7/LLY is a direct-fit, stacked-plate upgrade that lowers fluid temperatures for towing, fleet, and daily-driven trucks running the Allison 1000 transmission. Its 13-row core delivers 174% greater core volume and 192% greater fin surface area than the stock cooler, and CNC-machined adapters connect to the factory lines (or AN lines) for leak-free flow with direct-fit brackets and tailor-made hoses. Note: this cooler fits late-2003 trucks with purple line clips; early-2003 orange-clip trucks use the 2001-2003 cooler.
| Type | Direct-fit transmission cooler |
| Core | 13-row stacked-plate |
| Transmission | Allison 1000 |
| vs. Stock | +174% core volume, +192% fin area |
| Fittings | CNC-machined adapters (stock line or AN) |
| Note | Late-2003 purple-clip trucks only |
| Part Number | MMTC-DMAX-03SL |
| Warranty | Mishimoto Lifetime Warranty |
This part fits:
| Year | Make | Model | Submodel |
|---|---|---|---|
| 2003-2005 | Chevrolet | Silverado 2500 HD | Base |
| 2003-2005 | Chevrolet | Silverado 2500 HD | LS |
| 2003-2005 | Chevrolet | Silverado 2500 HD | LT |
| 2003-2005 | Chevrolet | Silverado 2500 HD | WT |
| 2003-2005 | Chevrolet | Silverado 3500 | Base |
| 2003-2005 | Chevrolet | Silverado 3500 | LS |
| 2003-2005 | Chevrolet | Silverado 3500 | LT |
| 2004 | Chevrolet | Silverado 3500 | WT |
| 2003-2005 | GMC | Sierra 2500 HD | Base |
| 2003-2005 | GMC | Sierra 2500 HD | SLE |
| 2003-2005 | GMC | Sierra 2500 HD | SLT |
| 2003-2005 | GMC | Sierra 2500 HD | WT |
| 2003-2005 | GMC | Sierra 3500 | Base |
| 2003-2005 | GMC | Sierra 3500 | SLE |
| 2003-2005 | GMC | Sierra 3500 | SLT |
| 2004-2005 | GMC | Sierra 3500 | WT |
Shipping: In-stock orders placed before 3 PM EST ship the same day, and everything else ships within 24 hours. Standard, expedited, and overnight options are available at checkout. Backordered items ship as soon as we get them back in stock. Contact us for lead times. See the full Shipping Policy.
Returns: 30-day returns on new, unused items in original packaging. See the full Refund Policy.
