The Blazer was introduced during the 1969 model year in both six-cylinder and V8, two and four wheel drive models. Chevrolet's new utility vehicle was designed to use proven components from the Chevrolet/GMC light truck line in a new size and body style. The GMC Jimmy was introduced in 1970.
There are three notably different Blazer/Jimmy body styles. The first, from 1969 through 1972, is easily identified by the rounded wheelwells. The second, from 1973 through 1975, has a high flat hood and rectangular wheelwells, as well as a generally squared-off shape. The third, from 1976, adds a fixed steel cab roof with rollover protection and replaces the frameless-glass doors with doors similar to those used on pickup trucks and Suburbans.
All four wheel drive Blazers and Jimmys have leaf springs at all four wheels. All two wheel drive models have coil spring independent from suspension with coil spring rear suspension through 1972, and rear leaf springs starting 1973. Numerous GVW packages have been offered to suit the suspension to the job. Vacuum assisted front disc brakes were introduced in 1971; earlier models had 11 inch diameter front drum brakes. All four wheel drive Blazers and Jimmys through 1972 use a conventional two-speed transfer case and all 1973-74 V8s and 1975-80 four wheel drive automatic transmission models use fulltime four wheel drive. Full time four wheel drive was dropped from manual transmission models early in the 1975 model year, and from automatic transmission models in 1981.