Engine assemblies are complete, factory-assembled engine units intended for vehicle replacement. These units comprise the core components – cylinder block, crankshaft, cylinder head(s), and associated internal mechanisms – required for power generation. Typically utilized in chassis replacement or major engine overhaul applications, they are offered as long blocks, complete assemblies (with ancillaries), or crate engines. Technical specifications include displacement, horsepower/torque ratings, valve configuration, and applicable vehicle model years/engines. Assemblies may feature pre-installed sensors, wiring harnesses, or fluid fill for simplified installation. Variations exist to meet differing emissions standards and performance levels.