GMPartsGiant.com offers the wholesale prices for genuine 2018 Buick LaCrosse parts. Parts like Automatic Transmission Differential Carrier are shipped directly from authorized GM dealers and backed by the manufacturer's warranty. Parts fit for the following vehicle options. Engine: 4 Cyl 2.5L, 6 Cyl 3.6L. Model Code: 4 DOOR CX EXT NOTCHBACK, 4 DOOR CXL EXT NOTCHBACK, 4 DOOR CXS EXT NOTCHBACK.