* Engine Mounts: The 360 and the 258 have completely different engine mount locations. You'll need custom motor mounts fabricated.
* Transmission: The 360 likely won't directly bolt to your existing transmission. You'll probably need a different transmission (likely an automatic, as adapting a manual would be complex), along with a custom adapter plate to connect the engine and transmission.
* Exhaust System: The exhaust manifolds and system will need to be custom-fabricated.
* Driveshaft: The driveshaft length will likely be incorrect and will need to be shortened or lengthened. The u-joints may also need replacing.
* Wiring Harness: The 360's wiring harness is different. You'll need to either modify your existing harness extensively or fabricate a new one, potentially with a stand-alone engine management system.
* Cooling System: The cooling system may need modifications to accommodate the 360's cooling requirements. A larger radiator might be needed.
* Steering: The larger engine might interfere with the steering components, requiring modifications or relocation of parts.
* Body Modifications: You may need to modify or trim parts of the engine bay to accommodate the larger 360.
* Strength: The YJ's frame might not be as robust as what a 360 would demand. Reinforcements could be necessary.
In short: While possible, this is not a weekend project. It's a major undertaking requiring significant mechanical skills, welding experience, fabrication expertise, and access to specialized tools and parts. It's far beyond a simple swap and will be costly in both time and money. You'd likely be better off seeking a professional mechanic experienced in engine swaps.
