Have Cummins, Will tow.
The dually factor is going to keep you off the trails and the rocks. The weight will keep you stuck in the mud. No real usefulness in it but does look sweat for a mall crawler. Again $20k is way to high. Figure 3-5k for a stock YJ (if in good shape), 2-3k in running gear and 2-3k for the motor. The work is not worth 10k.