Okay, enough devil's advocate for the 4L60E. Transmission Bench has a fantastic YouTube video that discusses the transmission's most common issues and their symptoms. Can't shift to third gear? It's likely the 3-4 clutch pack is burned up because the piston's rubber seals have gone bad. Is first gear the only one that engages? You probably have a broken drive shell. Does it shift harshly from first to second gear? The TCC regulator valve is likely worn out. Another frequent issue with 4L60Es is that their solenoids go bad. When this happens, shifts can become harsh or erratic. As for other members of the four-speed auto family, there's the 4L65E, which is what the 4L60E morphed into in 2001. GM upgraded the four-pinion carrier to a five-pinion version, improving the torque capacity. In trucks, the rating was 380 lb-ft, and in cars such as the 2005 Corvette, the torque rating was 400 lb-ft. The 4L70E is largely a 4L65E with a pump-mounted speed sensor and an upgraded torque capacity of 430 lb-ft, as per a 2005 New Product Announcement from GM. That transmission was put into vehicles such as the Chevy Trailblazer SS (400 lb-ft of torque) and Saab 9-7X Aero (a Trailblazer SS with plastic surgery and 395 lb-ft of torque). The 4L80E is the brawny big sibling that can handle 440 lb-ft of torque and gives wedgies to the 4L60E. Unfortunately for torquey performance car fanatics, GM only put the 4L80E in vans, trucks, and the Hummer H1. So if you want to drop $12,500 on a 1996 Chevy Impala SS and upgrade it to a 383 like Callaway did in the '90s, ripping out the 4L60E and swapping in a 4L80E is tough but doable.