4L60E Transmission Sonnax Heavy-Duty Pickup Build Package This Super High Quality Kit Contains Upgraded Parts Manufactured by Sonnax 4L60E-HDA (Heavy Duty Option A) kit includes: Line Pressure Booster Kit: This kit comes with the Pressure Booster Kit we will need to know if you have an early or late design pump in order to supply you with the right booster valve kit. The way to tell which it is you have is by the pump cover on the late one there is a cut-out in on section, where as in the early design it is just continuous See 2nd and 3rd images for reference in identifying the early and late pump covers. Sonnax hydraulic line pressure booster kits contain stronger pressure regulator springs and large ratio boost valves designed to work together to provide progressive pressure increases as driving conditions become more demanding. Our pressure regulator springs are approximately 10% stronger than OE and more conservative in impact than other aftermarket kit springs. Large ratio boost valves provide higher pressure incrementally and when it is needed the most. The combination of these springs and valves in a Sonnax kit gives you the best of both worlds: a modest pressure increase at the low end, with a high-end pressure that is equal to or greater than that of other aftermarket kit springs. Smart Shell 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 Smart Shell heavy-duty reaction shell kit 77749-02K is the only way to prevent shell failure AND protect the bearing. The Smart Shell 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 Smart Shell 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 accelerating from a stop in D3 shifter position. This change was made to improve coast down 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.