Jeep Grand Cherokee Laredo

the majority of the parts are interchangeable

It depends. If your motor is a 8 Cylinder or L6 4.0L, make sure the engines are the same. For example, if your 04 model had a 4.0L engine and your 99 had a 8 cylinder then certain parts such as the radiator would not be able to get swapped. But if they were the same type of engine then the mahority will be interchangable. Just make sure to check for rust before swapping :)