1977 GMC C35 180 Deg. Outlet Fitting|Unit Stamped: 3036684; 3036687; Position: Front;. 1978 GMC C35 Position: Front;. A/C Evaporator Core. Plate & Fin Evaporator Core. Evaporator Core. IMPORTANT: To confirm that this part fits your vehicle, enter your vehicles Year, Make, Model, Trim and Engine in the Compatibility Table.