made an offer to buy back the tooling and manufacturing line from AMC in April, 1974, and began building the engines on August 12. With production back within GM, Buick re-introduced the V6 that fall in certain 1975 models — a move made possible by the fact that foundations for the old V6 machinery were still intact at Buick's engine assembly plant in Flint, Michigan, so it was easy to put the old tooling back in place and begin production at least two years ahead of the normal schedule that would have been required to create new tooling. The bore was enlarged to , identical to the Buick 350 and Olds 307 V8s, yielding displacement. 78,349 units were installed in Buicks for 1975. Due to difficulties with the new fuel economy and emissions standards, the engine produced just . 1975 Buick Apollo 1975–1980 Buick Skyhawk 1975–1977 Buick Century 1975–1977 Buick Regal 1975–1976 Buick LeSabre 1975–1979 Buick Skylark 1975-1982 Oldsmobile Cutlass 1978–1981 Chevrolet Camaro 1978–1987 Chevrolet El Camino 1978–1983 Chevrolet Malibu Both the engine used in the Malibu starting in 1980 and the version first used in 1978 were NOT versions of the Buick 3800 Engine, but a different Chevy-built engine. Both the Buick V6 and the Chevrolet V6 are 90-degree V6 engines, and both are often referred to as being a 3.8 L V6. These engines should not be confused as being the same, and are unique engine designs. The Chevrolet V6 was essentially a small block Chevy V8 missing two cylinders. 1978–1987 Chevrolet Monte Carlo This is very confusing, as Monte Carlo at various times used both the V6 from the Buick engine as well as the V6 engine derived from the Chevrolet V8. 1978–1980 Chevrolet Monza 1978–1987 Oldsmobile Cutlass Supreme 1975–1980 Oldsmobile Starfire 1977–1979 Oldsmobile Omega 1978–1987 Pontiac Grand Prix 1976–1980 Pontiac Sunbird 1976–1981 Pontiac Firebird 1978–1981 Pontiac LeMans 1977–1979 Pontiac Ventura LD5 In 1978, GM began to market the 231 as the 3.8 liter as metric engine sizes became common in the United States. The RPO Code was LD5, though California-emissions versions were called LC6. Starting in 1979, the engine was used in the front-wheel drive Buick Riviera, though still with a longitudinal mounting. Larger valves and better intake and exhaust boosted the power output for 1979. A turbocharged version was introduced as the pace car at the 1976 Indianapolis 500, and a production turbo arrived in