4L60E Transmission Sonnax Heavy-Duty Pickup Build Package This Super High Quality Kit Contains Upgraded Parts Manufactured by Sonnax 4L60E-HDB Fits '94-later units (Heavy Duty Option B) kit includes: Performance Pack: The Sonnax Performance Pack is a must-have for any heavy-duty vehicle and the very best foundation for high-performance racing. All components work together to carefully tune line pressure, accumulator pressure and shift calibration. It’s the ultimate way to get an impressive transmission that responds to throttle and increased load with quick, firm shifts. · Consistent, firmer shifts under load without sacrificing low-speed drivability or guessing on calibration · Faster pressure increase and higher overall pressure for greater clutch/band holding power · Three ultra-reliable, patented, billet pinless accumulator pistons · Unique 1-2 accumulator spring combination for shifts with character · Improved high RPM pressure · Third accumulator valve gets the 2-3 right the first time, every time · Durable parts target commonly worn areas and prevent future damage to the accumulators and separator plate · The only way to eliminate PWM function without over-pressurizing converters (optional) Contains: Boost Valve with O-Ring .490", Elevated Pressure Regulator Spring, High RPM Pump Slide Spring, Spacer, 4th Servo Return Spring, Servo Cushion Spring, Servo Piston D-Ring Kit, 3-4 Accumulator Piston Kit, 3-4 Accumulator Spring, Servo Release Check Valve, Forward Accumulator Kit, 1-2 Accumulator Valve Shim, TCC Pressure Limiter Valve & Spring Optional, eliminates PWM/EC3 function, Checkballs (8) Separator Plate Plugs Not Shown, Twist Drills Not Shown, 1-2 Pinless Accumulator Piston Kit, 1-2 Accumulator Inner Spring, 1-2 Accumulator Outer Spring, 1-2 Accumulator Waved Spring SmartShell HD Reaction Shell Kit: In GM 4L60, 4L60-E, 4L65-E and 4L70-E units, bulky aftermarket shells always fall short when splines continue to strip and the shells break under stress. A chronic problem with both OE and thicker aftermarket shells is failure of the rear planetary bearing. From daily jobs to extreme builds, the Sonnax SmartShell heavy-duty reaction shell kit 77749-02K is the only way to prevent shell failure AND protect the bearing. The SmartShell avoids the weight found in traditional, heavy-duty aftermarket shells thanks to a unique combination of improved design and manufacturing for a super strength shell that's only slightly bulkier than OE. To prevent thrust loads from overwhelming the captured planetary bearing, the SmartShell features a larger bearing and custom roller clutch race. These parts re-route thrust loads through the carrier, completely bypassing the delicate bearing. Rear Stator Support Bushing: The original GM 4L60, 4L60-E, 4L65-E, 4L70-E rear stator bushing comes in narrow and wide versions in both common bronze and harder aluminum type materials. All versions commonly fail or wear out prematurely. Available aftermarket replacements typically have a poor quality fit and are also known to wear. For maximum durability Sonnax offers rear stator support bushing 77002BT-01, a better fitting and extremely wear-resistant, PTFE-lined bushing to stop future wear in its tracks. The Sonnax bushing is the best option for supporting the 20 lb. input housing and for improving the reliability of these common units. 4th Gear Super Hold Servo: Sonnax 4th gear super hold dual servo kit 77767K features 40% more apply surface area for greater holding power in GM 4L60, 4L60-E, 4L65-E and 4L70-E units. Vehicles with these transmissions often exhibit poor 3-4 shift quality and experience band failure in performance applications. Patented dual-piston design with 40% more apply delivers greater holding power D-ring seals prevent pressure loss Heavy Duty 2-3 Shift Valve: When the GM 4L60-E family of transmissions evolved from the 700-R4, the overrun clutch apply no longer applied in 1st and 2nd when acclerating from a stop in D3 shifter position. This change was made to improve coastdown drivability in D3, but had the side effect of reducing reduced the torque capacity of the input section. For greatly improved input sprag and Forward clutch durability, Sonnax heavy-duty shift valve 77754-41 for 4L60-E, 4L65-E and 4L70-E units will apply the overrun clutch in D3 1st, 2nd and 3rd gears.