Product Details

The OEM case bushing in vehicles with a THM 400 or 4L80-E transmission tends to walk-out of the housing bore. This allows the bushing to wander into the extension housing, leaves the output shaft unsupported, and may ruin the governor gear. The cause of this problem is the lack of a flange or stop surface on the case bushing to prevent the walk-out from occurring if the bushing begins spinning in the bore. The Sonnax case bushing 34006-SP is manufactured out of high-quality bronze bearing and is specially designed to remain in the case bore. This bushing has a flange on the transmission case side that prevents it from pushing completely through the bore. In addition, the flange accurately locates and helps retain the selective washer. The machined oil grooves allow for a supply of lubricating oil to enter the extension housing, as well as the transmission case.

The 4L80E and its variants were in production from 1991-2010 and can be identified by the 17-bolt oil pan and 4 forward gears.  Typically, this transmission is found in the heavier duty trucks and vans; mostly the 2500 and 3500 series.  It will also be found in the heavy half-ton, such as the 1500HD, SS, or Denali truck with the 6.0L

The 4L80E and 4L85E transmissions were found in the following GM labels and other brands; Chevrolet, Chevy, GMC, Hummer H1, Isuzu NPR, Jaguar, Aston Martin, Bentley, Rolls-Royce

These transmissions can be found in the following vehicles; however, you should double check your application with the 17-bolt pan count.  It is common for similar vehicles to have multiple transmission options available from the factory.

Chevrolet

• Avalanche 2500, 2002-2006
• Base Cab & Chassis, 2500, 3500, K2500, K3500, 1991-2009
• Express Van, 2500, 3500
• Silverado, Cheyenne, 2500, 3500, 2500 HD, K2500, K3500, 1991-2007
• Suburban, 2500 1996-2007
• Tahoe 6.0L, 8.1L 1995-2003

GMC

• Base Cab & Chassis, 2500, 3500, C2500, C3500, 1991-2009
• Savana Van, 2500, 3500
• Sierra, 2500, 3500, 2500HD, C2500, C3500, 1991-2007
• Yukon XL 6.0L, 8.1L 1995-2003

Hummer

• H1 1991-2005

Other

• Aston Martin DB7 1996-1999
• Bentley 1991-2006 (confirm 4-speed with 17 bolt pan)
• Isuzu NPR gas engine 1990-2007
• Jaguar XJS, XJS-R, XJ12 1993-1998
• Motor Homes 1995-2005
• Rolls-Royce 1992-2003

This transmission is part of the Turbo-Hydramatic series and also known by the following codes and model numbers: 4L80E, 4L80-E, MT1, 4L85E, 4L85-E, MN8

This transmission part fits the following years: 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, and 2013.