The 1968 Buick Skylark was one of the most significant model changes. Although it was still using the same basic chassis, all of GM’s mid-sized cars adopted a policy of using two different length wheelbases. Two-door models used a shorter wheelbase of 112 in, while four-door models used a longer wheelbase of 116 in. All of GM's mid-sized cars received all-new sheet metal.
The Gran Sport, previously an option package available on the Skylark, became a separate series. In a reshuffling of models in the lineup, the Special Deluxe replaced the previous Special. The Skylark nameplate was shuffled down a notch to replace the previous Special Deluxe. The previous Skylark was replaced by a new Skylark Custom.
The basic Skylark was available as a two-door hardtop coupe or a four-door sedan. The Skylark Custom came as a two-door convertible coupe, two-door hardtop coupe, four-door hardtop sedan, or four-door sedan.
The previous V6 was discontinued and the associated tooling was sold to Kaiser Industries, which used the V6 in its Jeep trucks and sport utility vehicles. The base engine in Buick Skylarks became a 250-cubic-inch inline six-cylinder engine using a 1-barrel Rochester carburetor that produced 155 hp at 4200 rpm.
Optional on the Skylark and standard on the Skylark Custom was a new 350 cubic inch V8 engine using a 2-barrel Rochester carburetor that produced 230 hp at 4400 rpm. This engine was based on the previous 300- and 340-cubic inch-displacement V8 engines.
Source: Wikipedia, 2012