Case bushing walkout and thrust washer wear are common issues in the GM 400, 4L80-E and 4L85-E units. Sonnax heavy duty case bushing kit 34006-SPB combines the tried and true no-walk case bushing with a high quality thrust bearing that replace the OE thrust washer and selective spacer to update this area for maximum durability in all applications. Selective shims are included for setting and adjusting rear end play.