Sonnax Heavy Duty Case Bushing Kit - SX34006-SPBTH400 HEAVY DUTY CASE BUSHING Suit GM TH400 Part Number: SX34006 SPB Case bushing walkout and thrust washer wear are common issues in the GM TH400, 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