8-Speed Automatic Transmission Assembly for 2021-2023 Ram 1500

A quick look at your own vehicle makes sure the right transmission shows up:

• Locate the transmission tag on the driver's side rear of the case and confirm the model is 8HP75.
• Confirm the truck is a 4x4 (four-wheel drive) model.
• Confirm the truck has a 5.7L Hemi V8 engine.
• Verify the truck does NOT have the eTorque system (check for a standard alternator vs. a large water-cooled motor-generator unit).
• Confirm the truck is the new style (DT generation) with 6-lug wheels.

What the install really takes — plan and budget with confidence:

Special tools this job needs:

• Heavy-duty transmission jack
• E-Torx socket set
• Fluid transfer pump
• OBD2 scan tool capable of reading real-time transmission fluid temperature and performing Quick Learn
• Security Gateway (SGW) bypass cable (for 2018+ Ram trucks)
• Infrared thermometer

Budget for these consumables at install:

• ZF LifeguardFluid 8 or Mopar 8 & 9 Speed ATF
• New integrated plastic oil pan assembly (includes filter, gasket, and new pan bolts)
• Torque converter seal (front pump input shaft seal)
• Rear output shaft seal
• Professional-grade transmission cooler line flush

What your vehicle’s computers will need after the swap:

What’s involved: VIN-locking, immobilizer alignment, and adaptive learn reset

The internal TCM is VIN-locked and tied to the truck's security/immobilizer system. Installing without programming will trigger security faults, limp mode, or lock the vehicle in Park. Programming requires a factory-level scan tool (like wiTECH 2.0) or a specialized module programmer. Alternatively, TCM cloning or swapping the original mechatronics unit can bypass VIN programming, though a diagnostic Quick Learn adaptive reset is still required.

Pro tips for a smooth first start-up — hand them to whoever does the install:

• Torque Converter Seating: Must feel/hear three distinct clicks to ensure full seating. Tightening bellhousing bolts with an unseated converter will crack the internal oil pump and destroy the transmission.
• Strict Fluid-Leveling Temperature Window: No dipstick. Fluid level must be checked via the side fill plug with the engine running only when fluid temperature is strictly between 30°C and 50°C (86°F to 122°F).
• Exhaust Y-Pipe Obstruction: Front exhaust Y-pipe must be dropped; flange bolts are prone to rusting and snapping.
• Manual Park Release Cable: Must be properly routed, connected, and calibrated after installation.
• Bellhousing Dowel Pins: Ensure alignment dowel pins are present and clean on the engine block to prevent pump damage or vibration.
• TCM Adaptive Relearn: A scan tool must be used to clear old adaptive values, followed by a specific drive cycle.

Easy to get right once you know them:

• eTorque vs. Non-eTorque Confusion: Buying a transmission from a non-eTorque truck for an eTorque truck (or vice versa) which uses a different torque converter and TCM calibration.
• Assuming Plug-and-Play Operation: Expecting the transmission to work without programming the replacement TCM to match the truck's VIN.
• Reusing the Old Oil Pan/Filter: Reusing the plastic pan will recirculate debris and clutch material from the previous failure into the replacement unit.
• Checking Fluid with the Engine Off: Opening the side fill plug with the engine off will cause several quarts of fluid to pour out, leaving the unit severely underfilled.
• Skipping the Cooler Flush: Reusing a contaminated cooler will immediately pump metallic particles into the replacement unit, causing rapid failure.
• Using the Wrong Fluid: Using generic universal ATF instead of the specified Mopar 8 & 9 Speed / ZF Lifeguard 8 fluid.

Not issues with the units on this page — the manufacturer documented these for every transmission of this family, wherever you buy one. Handy for your installer: