THE 550 68RFE transmission is built to handle the toughest demands, supporting up to 550 rear-wheel horsepower with high-strength billet hard part upgrades. Whether you're towing, daily driving, or using 35-inch or smaller tires, this transmission delivers reliable performance with firm, precise shifts and exceptional durability for the long haul.

Installation Available by our Team of Experts.

At RedLine Transmissions, we specialize in transmission installs for Dodge RAM Cummins. With over 2,100 installations completed, our expert team brings unmatched experience and craftsmanship to every build—driven by precision, pride, and meticulous attention to detail.

Hotflush Technology for a Clean Start

When installing, RedLine uses Hotflush machine technology to thoroughly clean transmission cooler lines and systems. This step removes all debris, clutch material, and contaminants that could damage a fresh build—something many shops skip. A clean system means your new transmission runs the way it should from day one.

Precision Install & Calibration

RedLine doesn’t just “bolt it in.” Every installation includes careful alignment, torque checks, and electronic calibration specific to your truck. We verify line pressures, fluid levels, and TCM settings so the transmission communicates perfectly with your engine and drivetrain.

Post-Install Testing & Validation

Before handing the keys back, RedLine performs road tests, relearn procedures, and live diagnostics to confirm drivability, shift quality, and overall performance. This ensures your truck leaves ready to work or play—without you being the test driver.

Expert Craftsmanship

Every transmission is hand-built by seasoned builders who understand the difference between “good enough” and “overbuilt.” We believe in going the overbuild route. Instead of rushing jobs or using cookie-cutter rebuild kits, RedLine takes the time to precision-machine, measure, and assemble each unit so it’s tuned to last tens of thousands of miles under real-world stress.

Specific Brand & Platform Knowledge

You don’t just “do transmissions.” You specialize in Cummins Dodge/RAM and Duramax Chevy/GMC platforms, which means you know the quirks, weak points, and exact part combinations that actually work in these trucks. This expertise ensures builds are not only stronger but also tailored for each application—whether it’s towing, daily driving, or performance horsepower.

Proprietary Build Recipes & Tested Combinations

RedLine has developed its own proven build recipes (THE 450, THE 550, THE 700, THE 1000, etc.) that eliminate factory weak points and balance performance with durability. These aren’t off-the-shelf packages—they’re field-tested setups refined over thousands of transmissions, backed by real-world data and customer feedback.

Real-World Testing & Validation

Before a RedLine transmission goes out the door, it’s not just assembled—it’s tested, validated, and proven under real-world conditions. From line pressure checks to hot flush verification and test-drives, every unit is verified to perform the way it should. This extra layer of quality control ensures customers drive away with confidence, knowing their build has already been put through its paces.