It´s a Diesel motor, I doubt it´s been done. Usually the engine swaps are for more power, 5.0 coyote for example. The 3.2 has way more torque but the hp is lower than the 4.0 V6. If you want economy do a research on LPG or Natural Gas systems. It will be way more cheap. With the Diesel engine I´m sure you´ll have to modify the whole fuel system, fuel pump, fuel lines, etc.