GMPartsGiant.com offers the wholesale prices for genuine 2021 Buick Envision 2WD parts. Parts like Automatic Transmission 2-9 And 4Th Clutch Piston Housing Assembly are shipped directly from authorized GM dealers and backed by the manufacturer's warranty. Parts fit for the following vehicle options. Engine: 4 Cyl 2.0L. Model Code: 1SC 4 DOOR SUV, 1SL 4 DOOR SUV, 1SV 4 DOOR SUV.