Full 4-Cylinder Piston Group : Engine rebuild package includes four standard size pistons matching rings wrist pins and retainers for a total top end rotating assembly replacement. Precision 102mm STD Bore Fitment: Specifically designed for Cummins 3.9L 4BT diesel motors using original factory specifications to ensure perfect cylinder wall clearance plus restored compression. Thermal Resistant Aluminum Construction: Manufactured from high-grade eutectic alloy providing superior durability under high boost conditions or extreme industrial work environments without warping. Verified Equipment Compatibility : Fits Case IH windrowers 8860 8870 along with various backhoes skid steers and stationary power units requiring genuine quality internal parts. Direct OEM Interchange References: Cross-listed with part numbers 3928673 and 3802747 to guarantee correct application for 1915 1902 1948 or 1961 series Critical Parts Lists.