The LS based GM small-block engine family is an engine design intended as the primary V-8 engine used in General Motors' line of rear-wheel-drive cars and trucks. The GM small-block series was a "clean sheet" design with only the rod bearings and bore spacing in common in terms of shared parts and dimensions with the classic Chevrolet small block V8. The basic layout owes a good deal to the essential concept of Ed Cole's original small-block design of 1954-55, though the small-block engine also uses design cues from Buick, Oldsmobile, and Pontiac engines. Some small-block engines are all-aluminum, especially the performance oriented engines, while others use cast iron blocks. The aluminum block engines use cast iron cylinder liners.