The 2020 Ram 3500 with 6.7L Cummins is a workhorse platform known for diesel reliability, but the 68RFE automatic transmission is its Achilles' heel—especially under heavy towing or tuning. Expect transmission-related issues to dominate your maintenance budget past 100,000 miles.
68RFE Transmission Overdrive and Torque Converter Clutch Solenoid Failures
Common · high severityTypical onset: 80,000-150,000 mi
Symptoms: Hard or delayed shifts between 5th and 6th gear, Transmission slipping or flaring RPMs on highway acceleration, Check engine light with P0871, P0743, or P0765 codes, Transmission overheating under load
Fix: Replace overdrive solenoid pack and torque converter clutch solenoid—requires pan drop, valve body removal, and full fluid flush. 4-6 hours labor. Often both solenoids fail together or within 10,000 miles of each other, so replace as a set to avoid double labor.
Estimated cost: $1,200-2,200
Torque Converter Shudder and Lockup Failure
Common · high severityTypical onset: 60,000-120,000 mi
Symptoms: Vibration or shudder at 40-50 mph during light acceleration, Feels like driving over rumble strips when converter tries to lock, Transmission temp spikes during towing, Metallic debris in transmission pan during fluid service
Fix: Torque converter replacement requires full transmission removal—8-12 hours labor. Inspect flex plate for cracks while trans is out. If caught early, sometimes a fluid flush with Mopar-spec ATF+4 and friction modifier buys time, butConverter failure is inevitable once shudder starts.
Estimated cost: $2,800-4,500
Transmission Cooler and Cooler Line Leaks
Occasional · medium severityTypical onset: 70,000-130,000 mi
Symptoms: ATF puddles under front of truck near radiator, Low transmission fluid warning or erratic shifting, Pink or red fluid mixed with coolant in overflow tank (if internal cooler fails), Transmission running hot even in normal driving
Fix: External cooler line replacement at frame rail or radiator connections—2-3 hours labor. If the internal radiator cooler fails, you're looking at radiator replacement plus full transmission flush to remove coolant contamination—adds 3-4 hours and potential internal damage if coolant mixed with ATF.
Estimated cost: $600-1,800
Transmission Mount Failure
Occasional · low severityTypical onset: 60,000-100,000 mi
Symptoms: Clunk or thud when shifting from park to drive or reverse, Excessive driveline vibration at idle in gear, Visible separation or tearing of rubber mount, Transmission tail housing sitting lower than normal
Fix: Replace transmission crossmember mount—requires supporting transmission on jack, removing crossmember bolts. 1.5-2 hours labor. Common on trucks used for heavy towing or with lift kits that increase driveline angles.
Estimated cost: $350-600
Premature Transmission Rebuild Due to Tuning or Towing Abuse
Occasional · high severityTypical onset: 100,000-180,000 mi
Symptoms: Slipping in multiple gears, especially 3rd-4th or 5th-6th, No reverse or delayed engagement after warming up, Metal shavings throughout transmission fluid, Burnt ATF smell and dark brown/black fluid color
Fix: Full transmission rebuild with upgraded clutch packs, solenoid pack, and valve body reconditioning. 12-16 hours labor plus core charge. The 68RFE was marginal from the factory for the Cummins torque output—tuning or frequent max-weight towing accelerates clutch pack wear exponentially.
Estimated cost: $4,500-7,000
Fuel Filter Restriction and Water Separator Issues
Common · medium severitySymptoms: Loss of power under load or at highway speeds, Hard starting or extended cranking, especially in cold weather, Check engine light with P0087 (fuel rail pressure too low), Water-in-fuel light illuminated on dash
Fix: Replace fuel filter cartridge and drain water separator—Cummins calls for every 15,000 miles but many owners stretch it to 20,000-25,000. 0.5-1 hour labor. Use OEM Mopar filters—aftermarket filters often lack proper micron rating and cause injector issues down the road.
Estimated cost: $150-280
Shift Cable Bushing Wear and Adjustment Issues
Occasional · low severityTypical onset: 80,000-140,000 mi
Symptoms: Shifter feels loose or sloppy with excessive play, Difficulty selecting park or reverse, may need to wiggle shifter, Gear indicator on dash doesn't match actual gear position, Transmission not going into park fully—rollaway risk
Fix: Replace shift cable and/or cable bushings at transmission end—bushings are plastic and wear out. 1-2 hours labor. Sometimes just adjustment at the transmission lever fixes it temporarily, but bushings will fail again within 10,000 miles.
Estimated cost: $250-500
Buy it if you need the Cummins pulling power, but budget $3,000-5,000 for transmission work by 120,000 miles—or plan a preemptive build if towing heavy.
AI-assisted summary drawn from NHTSA recall data, our labor-times database, and platform knowledge. Not a substitute for a pre-purchase inspection on a specific vehicle.