The 4L60-E came along in the mid-'90s, and shortly thereafter its design was changed from a three-piece construction to a two-piece design. Currently, the L60 and L65 have a separate, 360-degree bellhousing, which completely encloses the torque converter. This was done to increase powertrain stiffness and reduce vibration. The electronic versions of the transmission also use an electronically controlled capacity clutch, instead of a mechanical lock-up clutch. This design lets the computer decide on the necessary amount of slip, which maximizes fuel economy. SOURCES GMs Performance Parts « | 1 | 2 | 3 | 4 | View Full Article By Barry Kluczyk Enjoyed this Post? Subscribe to our RSS Feed, or use your favorite social media to recommend us to friends and colleagues!