Will a 1995 Chevy 350 and 1989 have the same wiring?

No, a 1995 Chevy 350 and a 1989 Chevy 350 will almost certainly not have the same wiring harnesses. While they might be the same basic engine, the supporting systems and electronic controls changed significantly between those years. The 1995 model year likely incorporated more sophisticated engine management systems (like OBD-II), which would necessitate a different wiring harness. Even if the engine itself were identical, the vehicle's electrical system will be different.