GMPartsGiant.com offers the wholesale prices for genuine 2018 GMC Acadia AWD parts. Parts like Automatic Transmission 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 2.5L, 6 Cyl 3.6L. Model Code: DENALI SUV, SLE SUV, SLE2 SUV, SLT SUV, SLT2 SUV.