OER Parts offers a wide selection of Automatic Trans & Components for your 1975 GMC C25. OER Parts offers 1975 GMC C25 Complete Transmission, 1975 GMC C25 Cooler Lines, 1975 GMC C25 Dipsticks & Tubes, 1975 GMC C25 Flex Plate, 1975 GMC C25 Gaskets, Seals, Filters & Hardware 1975 GMC C25 Modulator Valves, 1975 GMC C25 Shift Knobs, 1975 GMC C25 Shift Linkage, 1975 GMC C25 Shifters - OE, 1975 GMC C25 Shifters - Performance, 1975 GMC C25 Torque Converter & Covers, 1975 GMC C25 Transmission Pans, and 1975 GMC C25 Vacuum Lines.