6T75 Sun Shell 2011, used and ready to install. Fits the 6T75. Ships fast from the USA.
If your 2011 Traverse, Acadia, Enclave or Outlook with the heavy-duty 6T75 transaxle lost reverse, third and fifth, or the teardown turned up a shell with a cracked weld and chewed-up thrust surfaces, this is the replacement piece. It is a used GM sun shell pulled for the 2011 model year, sold so you can swap one damaged hard part instead of buying a full gear train.
The 6T70 and 6T75 are clutch-to-clutch six-speeds: five clutches and one one-way diode, with no shift valves and an internal control module doing all the work. The shell is the steel link between a clutch and a sun gear. Its lugged outer rim engages the clutch side, and the splined hub in the center drives the sun gear in the planetary set. When that clutch applies, torque passes through the shell and holds or drives the sun gear to produce the ratio. Because the hub is welded into a stamped shell, the weld is the weak point. The ATRA 6T70 issues seminar calls out shell weld breaks as a cause of no reverse, third or fifth, and notes that a new shell is supplied with the number 3 thrust bearing.
For 2011, the unit is a Gen 1 transmission. The major control update did not arrive until the 2013 model year, and GM revised the output and reaction carrier bearing pockets for 2009, so a 2011 gear train already carries those updated carriers. The shell itself is not on the list ATRA gives for 6T75 heavy-duty upgrades, which covers the output carrier, five-pinion carrier, wider transfer gear, differential carrier and ribbed case.
Keep it simple first. Unplug the transmission connector and try reverse. That tells you whether reverse is being blocked electrically. If reverse engages normally, the shell is not the problem and you are looking at a solenoid, pressure switch or wiring fault instead. If reverse is still missing with the harness disconnected, the failure is mechanical, and it is time to pull the pan and look for debris. Our 6T70 Acadia common problems guide walks through the P0776 and wave plate history, and the 6T70 problems and fixes overview covers the pressure switch faults that mimic a mechanical failure.
This listing is a 2011 GM sun shell for the 6T75. The 6T75 carries RPO codes MH6 (AWD) or MY9 (FWD) on the glovebox service label, while the lighter 6T70 uses MH2 or MH4. Lay your old shell next to the photo and match the lug count, the hub spline and the overall depth before installing. If you are not sure, send us your year and full VIN before you order and we will check it. Browse every 6T70 and 6T75 part we carry on the 6T70/6T75 collection page.
| Fits | 6T75 2011 |
| Part type | Sun Shell |
| Condition | Used |
| 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.
It is listed for the 2011 6T75. The shell is not one of the parts ATRA lists as a 6T75 heavy-duty upgrade, but you should still compare lug count, hub spline and depth against your old shell, or send us your year and VIN to confirm.
Unplug the transmission connector and select reverse. If reverse works unplugged, the fault is electrical or a pressure switch, not the shell. If reverse is still missing, the failure is mechanical.
The number 3 thrust bearing, any worn bushings and thrust washers, and updated wave plates in every clutch. Inspect the sun gear and reaction carrier for debris damage before reassembly.
Dexron VI automatic transmission fluid. Check the level with the transmission at normal operating temperature.
Yes. Clear codes and run the shift adapt relearn with a capable scan tool, then drive it through every gear so the control module learns the new clutch fill times.
