No, a 5.9L engine (likely referring to the Magnum V8) will not directly bolt into a 1998 Dodge Dakota 4WD without significant modifications. The 1998 Dakota 4WD came with either a 3.9L V6 or a 5.2L V8. While both are V8s, the 5.9L Magnum is a substantially different engine with different mounting points, bellhousing patterns, and overall dimensions.
You'd need to fabricate custom motor mounts, potentially modify the transmission, and likely deal with exhaust, wiring harness, and other compatibility issues. It's a major undertaking, far beyond a simple engine swap. It's generally not considered feasible for a home mechanic.
