I had that idea when I had my focus shell. You would have to go with a 4BT unless you do some serious modifications to the front end of the car to support the weight and lenght of the 6BT or ISB Cummins engine. I love the ISB Cummins thats in my truck, but the motor and transmission weigh in at almost 2000 pounds, with the motor being 1100 pounds dry weight.