Transmission Parts

BUSHING CASE SONNAX "NO WALK OUT" TH400, 4L80E, 4L85E The OE case bushing in vehicles with a GM THM-400, 4L80-E and 4L85-E transmissions tends to w...

Valve Body Checkballs – Set of 10 This set includes 10 high-performance checkballs (.250" size) made from durable, wear-resistant imidized plastic....

Sonnax Line Pressure Booster Kit for TH400 The Sonnax Line Pressure Booster Kit for the TH400 transmission is designed to enhance your vehicle’s pe...

Sonnax Case Saver Retainer for TH400 & '98-Earlier 4L80-E The Sonnax case saver retainer 34762-10 is the only intermediate clutch retaining rin...

Sonnax Planetary Rebuild Kit for 4L80-E, TH400 Transmissions Optimize the performance of your TH400 or '98-earlier 4L80-E transmission with the Son...