Limitations of the GM 4L60-E, 4L65-E, 4L70-E OE input housing are the root cause of 3-4 burnup in performance applications. The weak OE backing plate flexes during clutch apply, allowing heat to build up unevenly within the clutch pack’s limited space. Stop the flex and you stop 3-4 clutch failure. Sonnax Smart-Tech input housing kit 77733-06K makes room for a taller clutch pack anchored in place by a stronger backing plate, making it the only way to increase clutch capacity and protect against destructive heat. Numerous other improvements to the housing ensure maximum durability and protection against failure in higher horsepower, higher pressure applications. The housing also is available with a pre-installed, heavy-duty input shaft. Anchored backing plate keeps clutches parallel to stop the flexing and distortion that leads to heat build-up Treated housing is significantly more resistant to fatigue failure Steel reinforcement sleeve prevents breakage in the spline area Custom backing plate replaces OE retaining ring to eliminate risk of blowout This kit comes with Alto's Top of the line High Performance G3 3-4 Powerpack clutches specifically designed for Sonnax Smart-Tech drum. Note Requires '91-later 3-4 apply ring; requires '97-later ring gear; requires '97-later dual-cage return spring; requires '97-later stamped steel forward piston. Cannot be used with aluminum forward piston or Sonnax billet forward piston 77764-01. See instructions for further detail. Contents: PTFE Impregnated Rear Stator Support Bushing Modified Input Housing Input Drum Reinforcement Sleeve Overrun Piston Inner Seal 3-4 Clutch Apply Plate 3-4 Clutch Return Springs (10) Bolt-on Anchor Plate Overrun Piston Outer Seal Socket Head Cap Screws (15) Overrun Piston