Sonnax Smart-Tech 4L60, 4L60E Input Housing Kits w/Heavy Duty 298MM Input Shaft The Sonnax Smart-Tech tackles ALL the 3-4 clutch issues of the 4L60 as no other housing has done before! Although incremental improvements to aftermarket parts have been made addressing 4L60-Series 3-4 clutch problems, they failed to keep pace with steadily increasing power levels of modern performance engines... until now! Limited 3-4 Clutch Capacity- Anchor (backing) plate works with redesigned apply plate for more room and clutch options for eight or nine frictions for increased torque capacity. 3-4 Backing Plate Flexing & Distortion- Zero-Flex, bolt-on anchor plate replaces OE backing plate to eliminate clutch pack distortion and uneven clamping pressure. Input Housing Fatigue Failure- Treated housing is significantly more resistant to fatigue and failure. 3-4 Retaining Ring Blow-Out- Fifteen bolts secure anchor plate, eliminating snap-ring and blow-out concerns.