Will a 4.6L engine from 2000 mustang fit in 3.8L v6?

No, a 4.6L V8 from a 2000 Mustang will not simply fit into the engine bay of a Mustang originally equipped with a 3.8L V6. While both are Mustangs, the engine bays are designed differently to accommodate the different engine sizes and configurations. You'd need significant modifications, likely including:

* Motor Mounts: The mounting points for the 4.6L are in completely different locations. Custom motor mounts would be required.

* Transmission: The 4.6L typically uses a different transmission than the 3.8L. You'd need to swap the transmission as well, potentially necessitating modifications to the transmission tunnel.

* Wiring Harness: The wiring harnesses are entirely different. A new harness or extensive rewiring would be necessary.

* Exhaust System: The exhaust system will not fit. A new system would be required.

* Cooling System: The cooling system might need modifications or replacement to handle the larger engine.

* Other Components: Other components like the power steering system, air conditioning system, and accessories may also require modification or replacement.

In short, while it's *theoretically* possible with extensive fabrication and modification, it's a very major undertaking, far beyond a simple engine swap. It would be a very costly and time-consuming project. It's usually simpler and more cost-effective to find a Mustang that already came with the 4.6L engine.