Still in production, the 700R4 / 4L60E transmission is one of the most popular GM RWD transmissions of the 80's & 90's. The early 80's 700R4 was plagued with issues, but after 1987 most of the issues were addressed in production.
In 1993, the fully electronic 4L60E transmission was introduced which requires a computer to operate. With the 4L60E, it is imperative to follow the interchange rules because of solenoid & design changes by year. For example, the 93-94 4L60E will interchange, 1995 Non-PWM will only interchange with the 1995 Non-PWM, the 1995 PWM will only interchange with 1995-1997 PWM, 1998+ will interchange (except for removable bellhousing).