1991 Buick Reatta Engine: 3.8L V6; 1.560 In. Part Type: Engine Coolant Thermostat Seal. Engine Coolant Thermostat Housing Gasket. Eng Coolant Gasket. Compatible Years: 1991. Ensure that this part fits your vehicle by entering your vehicle's Year, Make, Model, Trim, and Engine in the Compatibility Table.