• Must be used with '97-later stamped steel forward piston. Cannot be used with '96-earlier aluminum forward piston or Sonnax billet forward piston 77764-01.
  • This kit must be used with a '97-later dual-cage return spring (24206085). See instructions for details.

4L60, 4L60-E

Reinforced Input Housing Kit with Heavy Duty Input Shaft
Part No. 77733-13K

Fits 298mm units only

OE Part No. 17803689, 08663580

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Sonnax reinforced OE input housing and heavy duty input shaft kit 77733-13K is a great upgrade for GM 4L60, 4L60-E high performance and heavy-duty applications. The shaft is made of specially heat-treated steel with very hard outer layers and a more ductile inner core for strength and resistance to fracture. Feed holes are chamfered to reduce stress and the shaft is further processed by shot peening and deep cryogenic treatment.

The high-strength 298mm style input shaft and OE housing comes with a reinforcement sleeve installed on the housing to strengthen the aluminum splines, which are otherwise prone to cracking. This kit includes a custom-manufactured overrun piston that is designed to be used only with a stamped steel forward piston, eliminating the need to use OE cast forward piston or aftermarket billet forward piston.

For greater levels of performance, Sonnax offers a Smart-Tech® input housing kit with heavy duty input shaft, 77733-11K, that features additional input housing and 3-4 upgrades.

  • All new drum and high-strength shaft assembly
  • 57% harder than standard OE shaft
  • Compatible with stamped steel forward pistons
  • Reinforced input drum
  • Overrun Piston
  • Overrun Piston Inner Seal
  • Overrun Piston Outer Seal
  • Input Housing with 298mm Input Shaft Assembly
  • Input Drum Reinforcement Sleeve (installed)
  • 4L60, 4L60-E Reinforced Input Housing Kit with Heavy Duty Input Shaft 77733-13K