The K5 Blazer was the smallest full size SUV version of the General Motors C/K Trucks family. Introduced to the Chevrolet line in 1969, the full-size Blazer was replaced in 1995 by the Chevrolet Tahoe. In 1970, GMC introduced its own model of the truck, called the Jimmy, which lasted until the 1992 GMC Yukon. Both were based on the short wheelbase trucks and were available with either rear-wheel drive or four-wheel drive. The Blazer's long wheelbase relative (with an integrated rear body, and doors for 2nd row passengers) is known as the Chevrolet Suburban.
The K5 Blazer and Jimmy had "full convertible" removable tops until 1975. In 1976, GM introduced a half-cab design that was less prone to leaks and slightly safer in a roll-over. These half cabs are convertible starting at a few inches behind the driver/passenger doors all the way back to the tailgate. In 1992, the Blazer was redesigned completely and no longer had a removable top.
Smaller models, the S-10 Blazer and S-15 Jimmy, were introduced alongside these trucks in 1983. The original Blazer and Jimmy remained in production until 1991; 1992 saw the introduction of a new K1500 Blazer (and the rebadged GMC Yukon) on the GMT400 platform. After 1994, the Blazer was renamed the Chevrolet Tahoe and it was offered in a two-door model up until 1999. After that it was offered only with four passenger doors.
Source: Wikipedia, 2011