Engine Block Heaters are used to heat the engine block and engine fluids of gas and diesel vehicles as an aid to starting in cold weather. The heater is operated using standard household AC power and the heat generated is distributed throughout the engine by the convective flow of the warmed coolant. -- Agricultural, Industrial & Heavy Duty Applications: Caterpillar 3406 (Except 1998 models), 3406 (with BrakeSaver-through 1993 models), 3406E. Not for use with 1998 3406E or 15.8 Liter 600 HP engine. Without BrakeSaver: Replaces 1" pipe plug in oil cooler rear bonnet. With BrakeSaver: Install in front bonnet. 3408 (1099 C.I.D.). Replaces 1" pipe plug behind oil cooler on Right cylinder bank. C9, C15, C16. Install in oil cooler rear bonnet. Detroit Diesel 6V-71, 8V-71 Vehicles without power steering and/or air conditioning. Replaces 1" pipe plug on front face of Left cylinder bank. Series 50 (Except low-mount turbo). Replaces 1" NPT plug in oil cooler casting. Engine may also accept oil pan heater 8603243. Series 60 (11.1 Liter, 677 C.I.D., 12.7 Liter, 775 C.I.D.). Pre-1991 engines: Replaces 1" NPT plug in water pump outlet casting on Right front side of engine. 1991 & Newer engines: Replaces 1" pipe plug near top front of oil cooler. May also accept oil pan heater 8603243. International/Navistar V800 (798 C.I.D.) . Replace 1" pipe plug in oil cooler bonnet. Perkins 640 (Z Series 8 Cylinder). Install in Left Rear (LR).