Sonnax kit SC-4R100HD has been discontinued and replaced by the HP-4R100-01 Performance Pack. Formerly a popular Sure Cure® option, this heavy-duty kit for Ford 4R100 units has been further refined to become a Performance Pack. This kit offers innovative, heavy-duty calibration for firmer shifts under load without sacrificing low-speed drivability. Precision components upgrade the 4R100 for maximum performance and durability by recalibrating pressures and shift accumulation. Durable, improved parts target commonly worn areas in the transmission to repair damage and prevent future wear and tear. Recalibrated shift accumulation, with tunability for great HD shifts Improved accumulator valves for greater clutch durability Improved pump components to minimize leaks and maintain pressure, TCC performance and lube Sure Lock overdrive retaining ring prevents loss of 4th Includes internal parts for setup and to prevent common failures Contents 1-2, 2-3 & 3-4 Accumulator Control Valve Kits Heavy Duty Low/Reverse Modulator Sleeve Kit Line Pressure Booster Kit Line-to-Lube Pressure Regulator Valve TCC Control Plunger Valve Kit Front Lube/Drainback Valve Kit Line Pressure Modulator Plunger Valve Kit One-Piece Rear Case Bushing Center Support Gasket Intermediate & Direct Clutch Feed Seal Kit High Radius Relief Valve Rear Planet Endplay Shims (2) Performance Rated Accumulator Springs Green Springs (2), Yellow Springs (2), Red Springs (3), Non-Painted Springs (3) Sure Lock Overdrive Spiral Snap Ring