Will a 98 Cadillac STS Northstar motor go into 02 STS?
No, a 1998 Cadillac STS Northstar engine will not directly bolt into a 2002 Cadillac STS. While both are Northstars, the engine and associated components changed significantly between those model years. The engine mounts, wiring harnesses, and computer systems are incompatible. You'd need a massive amount of custom fabrication and potentially a significant amount of electrical re-work, making it a practically infeasible swap.