6L90 Sun Shell 2007, remanufactured and ready to install. Fits the 6L90. Ships fast from the USA.
Model year 2007 was the first year GM put the 6L90 into production, behind the 6.0L gas V8 in the new Chevrolet Silverado and GMC Sierra 2500HD and 3500HD. If your launch-year heavy-duty truck has lost Reverse, drops third or fifth, or is throwing bronze and steel onto the pan magnet, the sun shell in the rear gearset is one of the parts that gets inspected first. This one is a remanufactured GM part, so you are installing a cleaned, inspected and service-ready assembly rather than a core pulled straight out of another worn transmission.
The 6L90 uses the Lepelletier layout: a simple planetary at the front whose sun gear is anchored to the stator support, feeding a Ravigneaux compound set at the rear. That rear set has two sun gears, a small forward sun and a large reverse sun, sharing long and short pinions and one ring gear. The sun shell is the drum-shaped member that carries the large sun gear and ties it to the clutches that act on it. When the 3-5-R clutch drives it you get third, fifth and Reverse; when the 2-6 clutch holds it you get second and sixth. Five of the seven ranges (second, third, fifth, sixth and Reverse) depend on that one shell staying in one piece, which is why a cracked shell or stripped spline shows up as several missing gears at once. GM lengthened the 6L90 case by 1-3/8 inch over the 6L80 to fit stronger input and output gearsets, and this part is sized for that heavier unit.
Several cheaper faults copy these symptoms, so rule them out first. Low fluid, a stuck 3-5-R regulator valve, a misplaced checkball after a valve body job and a solenoid fault in the TEHCM can all cause no Reverse or flared shifts without a single broken hard part. Our 6L90 Silverado 2500 shift problems guide walks through the scan data and pressure checks to run. If the pan shows heavy metal, or an air check holds on the 3-5-R and 2-6 circuits but the gear still is not there, the gear train has to come apart and the shell, its splines and its welds can be inspected directly.
This shell is listed for the 2007 6L90 (RPO MYD). In 2007 that means the GMT900 Silverado and Sierra 2500HD/3500HD with the 6.0L. GM revised the 6L family during production, and 6L80 and 6L90 parts are not interchangeable even when they look close: ATSG documents fifteen components that differ in size between the two. Compare the listing photo, spline counts and overall height with the part you remove, and confirm the RPO on your glovebox label. If you are not sure, send us your year and VIN. Every other 6L90 hard part we stock is in the 6L90 collection.
For the full list of what wears out on these trucks, see 6L90 common problems and fixes.
| Fits | 6L90 2007 |
| Part type | Sun Shell |
| Condition | Remanufactured |
| Brand | GM |
| Ships | From the USA |
| Warranty | 1-year |
Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
In 2007 the 6L90 went into the GMT900 Chevrolet Silverado and GMC Sierra 2500HD and 3500HD with the 6.0L gas V8. Check for RPO MYD on the glovebox label or send us your VIN.
No. The 6L90 has a longer case and heavier gearsets, and several internal parts are dimensionally different from the 6L80. Use a part made for the 6L90.
Yes. The shell carries the sun gear that the 3-5-R clutch drives for Reverse, so a cracked shell or stripped spline can take out Reverse along with third and fifth. Rule out valve body and TEHCM faults first.
Frictions, steels and seals from a rebuild kit, the thrust bearings and washers you disturb, the filter and seal, and any drum or hub with damaged splines or cracked welds.
DEXRON-VI, with the level set hot at the check plug. Reset the transmission adapts with a scan tool and road test through every gear.
