The Napa Echlin ST45 is a 4-terminal starter solenoid designed to fit 1984-1992 Cummins 6BT 5.9L engines. It features a bolt-on mounting style and is a genuine NAPA product. The solenoid is manufactured in China with a matte finish and is part of the Starter Motor Parts category. Its OE/OEM part number is 5594, and it is interchangeable with various part numbers such as 938F and STSB1053. This solenoid is not a vintage part and does not have universal fitment. It comes with a California Prop 65 warning for cancer and reproductive harm.