TH400/4L80E/4L85E Transmission SONNAX No Walk Out Case Bushing The OE 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 and cause case damage. Sonnax bushing 34006-SP is specially designed to remain in the case bore. Width: 0.690" Housing Bore: 2.129" Shaft Dia.: 2.006" High-quality bearing bronze Flange on the transmission case side prevents bushing from pushing completely through the bore Flange accurately locates and helps retain the selective washer Machined oil grooves allow for a supply of lubricating oil to enter the extension housing as well as the transmission case. NOTE: The housing bore should measure between 2.1285"/2.1295" in diameter for an ideal fit. When damage to the case is so severe that bore diameter is larger than 2.129", use Sonnax oversized case bushing 34006-OS. See instructions for details.