8-Speed Automatic Transmission Assembly for 2016-2017 Chevrolet & GMC
Product Notes Read before buying
This is an 8-speed automatic transmission (GM RPO code M5U). It fits 4-wheel drive models with the 5.3L V8 engine only. Please verify your vehicle has the 8-speed transmission before ordering, as a 6-speed version was also available and they are not interchangeable.
Voice or type your vehicle details and Wrenchy will confirm fitment in seconds.
Vehicle Fitment Guide
This part fits the following vehicles:
| SubmodelSUB- MODEL |
Body Style | Years | Engine | Attributes |
|---|---|---|---|---|
| Custom | Crew Cab Pickup | 2016 | V8 5.3L FLEX | 4WD | Automatic |
| Custom | Crew Cab Pickup | 2016 | V8 5.3L | 4WD | Automatic |
| Custom | Extended Cab Pickup | 2016 - 2017 | V8 5.3L FLEX | 4WD | Automatic |
| Custom | Extended Cab Pickup | 2016 - 2017 | V8 5.3L | 4WD | Automatic |
| High Country | Crew Cab Pickup | 2016 - 2017 | V8 5.3L FLEX | 4WD | Automatic |
| High Country | Crew Cab Pickup | 2016 - 2017 | V8 5.3L | 4WD | Automatic |
| LS | Crew Cab Pickup | 2016 | V8 5.3L MILD HYBRID EV-GAS (MHEV) | 4WD | Automatic |
| LS | Crew Cab Pickup | 2016 - 2017 | V8 5.3L | 4WD | Automatic |
| LS | Crew Cab Pickup | 2016 - 2017 | V8 5.3L FLEX | 4WD | Automatic |
| LS | Extended Cab Pickup | 2016 - 2017 | V8 5.3L FLEX | 4WD | Automatic |
| LS | Extended Cab Pickup | 2016 - 2017 | V8 5.3L | 4WD | Automatic |
| LS | Extended Cab Pickup | 2016 | V8 5.3L MILD HYBRID EV-GAS (MHEV) | 4WD | Automatic |
| LS | Standard Cab Pickup | 2016 | V8 5.3L MILD HYBRID EV-GAS (MHEV) | 4WD | Automatic |
| LS | Standard Cab Pickup | 2016 - 2017 | V8 5.3L | 4WD | Automatic |
| LS | Standard Cab Pickup | 2016 - 2017 | V8 5.3L FLEX | 4WD | Automatic |
| LT | Crew Cab Pickup | 2016 - 2017 | V8 5.3L FLEX | 4WD | Automatic |
| LT | Crew Cab Pickup | 2016 - 2017 | V8 5.3L MILD HYBRID EV-GAS (MHEV) | 4WD | Automatic |
| LT | Crew Cab Pickup | 2016 - 2017 | V8 5.3L | 4WD | Automatic |
| LT | Extended Cab Pickup | 2016 - 2017 | V8 5.3L | 4WD | Automatic |
| LT | Extended Cab Pickup | 2016 - 2017 | V8 5.3L FLEX | 4WD | Automatic |
| LT | Extended Cab Pickup | 2016 - 2017 | V8 5.3L MILD HYBRID EV-GAS (MHEV) | 4WD | Automatic |
| LT | Standard Cab Pickup | 2016 - 2017 | V8 5.3L FLEX | 4WD | Automatic |
| LT | Standard Cab Pickup | 2016 - 2017 | V8 5.3L MILD HYBRID EV-GAS (MHEV) | 4WD | Automatic |
| LT | Standard Cab Pickup | 2016 - 2017 | V8 5.3L | 4WD | Automatic |
| LTZ | Crew Cab Pickup | 2016 - 2017 | V8 5.3L | 4WD | Automatic |
| LTZ | Extended Cab Pickup | 2016 - 2017 | V8 5.3L | 4WD | Automatic |
| SSV | Crew Cab Pickup | 2016 - 2017 | V8 5.3L FLEX | 4WD | Automatic |
| SSV | Crew Cab Pickup | 2016 - 2017 | V8 5.3L | 4WD | Automatic |
| WT | Crew Cab Pickup | 2016 - 2017 | V8 5.3L | 4WD | Automatic |
| WT | Crew Cab Pickup | 2016 - 2017 | V8 5.3L FLEX | 4WD | Automatic |
| WT | Extended Cab Pickup | 2016 - 2017 | V8 5.3L FLEX | 4WD | Automatic |
| WT | Extended Cab Pickup | 2016 - 2017 | V8 5.3L | 4WD | Automatic |
| WT | Standard Cab Pickup | 2016 - 2017 | V8 5.3L | 4WD | Automatic |
| WT | Standard Cab Pickup | 2016 - 2017 | V8 5.3L FLEX | 4WD | Automatic |
| SubmodelSUB- MODEL |
Body Style | Years | Engine | Attributes |
|---|---|---|---|---|
| Base | Crew Cab Pickup | 2016 - 2017 | V8 5.3L | 4WD | Automatic |
| Base | Crew Cab Pickup | 2016 - 2017 | V8 5.3L FLEX | 4WD | Automatic |
| Base | Extended Cab Pickup | 2016 - 2017 | V8 5.3L | 4WD | Automatic |
| Base | Extended Cab Pickup | 2016 - 2017 | V8 5.3L FLEX | 4WD | Automatic |
| Base | Standard Cab Pickup | 2016 - 2017 | V8 5.3L | 4WD | Automatic |
| Base | Standard Cab Pickup | 2016 - 2017 | V8 5.3L FLEX | 4WD | Automatic |
| Denali | Crew Cab Pickup | 2016 - 2017 | V8 5.3L | 4WD | Automatic |
| SLE | Crew Cab Pickup | 2016 - 2017 | V8 5.3L | 4WD | Automatic |
| SLE | Crew Cab Pickup | 2016 - 2017 | V8 5.3L FLEX | 4WD | Automatic |
| SLE | Extended Cab Pickup | 2016 - 2017 | V8 5.3L FLEX | 4WD | Automatic |
| SLE | Extended Cab Pickup | 2016 - 2017 | V8 5.3L | 4WD | Automatic |
| SLE | Standard Cab Pickup | 2016 - 2017 | V8 5.3L | 4WD | Automatic |
| SLE | Standard Cab Pickup | 2016 - 2017 | V8 5.3L FLEX | 4WD | Automatic |
| SLT | Crew Cab Pickup | 2016 - 2017 | V8 5.3L FLEX | 4WD | Automatic |
| SLT | Crew Cab Pickup | 2016 - 2017 | V8 5.3L MILD HYBRID EV-GAS (MHEV) | 4WD | Automatic |
| SLT | Crew Cab Pickup | 2016 - 2017 | V8 5.3L | 4WD | Automatic |
| SLT | Extended Cab Pickup | 2016 - 2017 | V8 5.3L | 4WD | Automatic |
| SLT | Extended Cab Pickup | 2016 - 2017 | V8 5.3L FLEX | 4WD | Automatic |
| SLT | Extended Cab Pickup | 2016 - 2017 | V8 5.3L MILD HYBRID EV-GAS (MHEV) | 4WD | Automatic |
| Denali | Crew Cab Pickup | 2017 | V8 5.3L FLEX | 4WD | Automatic |
Know This Transmission Before You Buy
The research behind our purchase interview — recalls, bulletins and real install economics for this transmission family:
A quick look at your own vehicle makes sure the right transmission shows up:
- Verify RPO code M5U on the glove box sticker (MYC is a 6-speed and will not fit).
- Confirm the vehicle is a 4x4 (4WD) model.
- Verify the 8th digit of the VIN is 'C' (designating the 5.3L L83 V8 engine).
- Locate the white barcode sticker on the passenger side of the transmission case and match the 4-character model code to 6U3L, 6U8L, or 6ULL.
What the install really takes — plan and budget with confidence:
Special tools this job needs:
- Heavy-duty transmission jack and engine support stand
- GM-compatible scan tool (GDS2 or equivalent) with J2534 pass-thru capability
- Fluid transfer pump
- Transmission cooler line flush kit / exchange machine
Budget for these consumables at install:
- Mobil 1 Synthetic LV ATF HP (Blue Label, GM Part #19417577 or 19300536)
- New internal transmission filter and pan gasket
- New front pump/torque converter seal
- Professional-grade transmission cooler flush solvent
What your vehicle’s computers will need after the swap:
What’s involved: Solenoid Characterization Programming (TUN Calibration), Transmission Service Fast Learn (Adaptive Relearn), and Adaptive Learning Drive Cycle
The GM 8L90 uses a unique current modulation algorithm to control its solenoids. You must program the new transmission's Transmission Unique Number (TUN) into your vehicle's TCM using GM's Service Programming System (SPS2) via a GM-specific scan tool. Follow this with a Transmission Service Fast Learn and an Adaptive Learning Drive Cycle.
Pro tips for a smooth first start-up — hand them to whoever does the install:
- Torque Converter Seating: Ensure the torque converter is fully seated (typically 3 distinct clicks) before bolting to the engine to avoid cracking the pump housing.
- Exhaust Y-Pipe Obstruction: The exhaust Y-pipe runs directly beneath the transmission pan and must be unbolted or pried out of the way to service the pan.
- No Dipstick / Strict Fluid Level Procedure: Fluid level must be checked via a standpipe plug in the bottom of the pan strictly when fluid temperature is between 35°C and 45°C (95°F to 113°F).
- Cooler Thermostat Bypass: The factory thermal bypass valve opens late (~194°F). Installing an updated GM bypass valve (158°F) or delete kit is highly recommended.
Easy to get right once you know them:
- Using Dexron VI Fluid instead of Mobil 1 Synthetic LV ATF HP (Blue Label).
- Skipping the TUN Programming and Service Fast Learn.
- Cracking the pump during installation by not fully seating the torque converter.
- Ordering a 2WD transmission for a 4WD truck.
- Attempting to swap a 6.2L transmission into a 5.3L truck.
- Reusing torque-to-yield torque converter bolts.
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:
🔎 Recommended at install: Complete transmission fluid flush and exchange using updated Mobil 1 Synthetic LV ATF HP (Blue Label) fluid per TSB #18-NA-355.
🔎 Recommended at install: Transmission Service Fast Learn procedure using a professional scan tool to reset and recalibrate adaptive pressure commands per TSB #16-NA-019.
🔎 Recommended at install: Requires replacing the valve body or installing upgraded sleeves per TSB #19-NA-266.
🔎 Recommended at install: Address pump failures related to torque converter hub wear.
Researched from factory recalls, TSBs and OEM service data (reference unit 400-05259-5440470). Unit-specific details — mileage, condition, warranty, freight — are covered in the checkout interview.
Policies, in plain English.
Shipping & Handling
- Ships by LTL freight on a pallet — a real freight truck, not a parcel van
- Your checkout freight quote covers delivery to your door (liftgate service included for residential addresses)
- The carrier calls ahead to schedule a delivery window — someone must be present to receive it
- Typically palletized and picked up within 2–3 business days; transit time depends on distance
120-Day Warranty
This part includes a 120-day warranty.
- If the part fails within the warranty window, we'll replace it or refund per the coverage terms
- Coverage is parts-only — installation labor is not included
- Warranty covers defects — not installation errors, misuse, or damage after installation
Your pre-purchase interview reviews these exact terms with you before anything is charged.
Returns (30 Days)
We accept returns of uninstalled parts within 30 days of delivery for this part.
- Defective parts: We will replace the part or issue a refund at our discretion
- Programming: "Needs to be programmed to my vehicle" is not a valid return reason. Many modules require dealer programming — we're happy to help connect you with resources if your dealer says it's not programmable
- Return shipping: This part ships by freight (LTL) — the part price is refundable per the terms above, but shipping costs are non-refundable and return freight follows the seller's return terms. Your pre-purchase interview walks through the exact numbers before you buy
- Parts must be returned in original packaging and unmodified condition
- Poorly packaged returns that arrive damaged will not be credited
Damaged in Shipping?
Freight damage is rare — and you're fully protected when you do two things at delivery:
- Inspect before you sign — you're allowed time to look the pallet over while the driver waits
- Write any damage on the delivery receipt before signing — that one line is what makes a freight claim succeed
- Severe damage? Refuse the delivery — it goes back at no cost to you and we make it right
- Photograph the pallet before unwrapping; report concealed damage within 24 hours of delivery
We handle the carrier claim — you just help document it. Your pre-purchase interview walks through this checklist too.
Order Cancellation
Cancel before shipment for a full refund. Once the pallet has been built, a preparation charge may apply — and once the freight carrier picks it up, shipping costs are non-refundable and standard return terms apply. Your pre-purchase interview shows the exact numbers before you pay.
Expert Guides
2016-2017 Silverado & Sierra 1500 5.3L 4WD 8L90 Transmission: Problems, Identification, and Used Replacement
Identify the exact 8-speed 8L90 transmission for your 5.3L 4x4 truck, understand the "Chevy Shake" and other common failures, and learn when to replace it with a quality used OEM unit.
Read Full Guide →Related Trouble Codes (OBD-II)
32 matching guidesIf your scan tool is showing one of these trouble codes, this part is a common fix. Each guide explains the code, how to diagnose it, and exactly what to replace.
Miscellaneous Information
OEM Part Numbers:
GM: 19330114, 19433304, 19434869, 24271485, 24273214, 24274902, 24274905, 24281108, 24293326
Other: 6U3L, 6U8L, 6ULL
Fits Years: 2016 2017
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Nearly two decades of shipping parts to professionals & enthusiasts.
Backed By The Selling Yard
This unit ships with the selling yard's 120-day warranty. Longer plans can be requested during checkout.
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