[Mickeymotormount]

As Clovis stated, you can leave the trans and transfer case in provided you know it's in good working order. Just be sure to remove the torque converter to ring gear bolts before undoing the bell housing bolts. Once the torque converter bolts are out, you can usually slide the converter back about a 1/4 inch and leave it there. Then you can take out the bell housing bolts. As Clovis said, be sure to have a floor jack with a piece of plywood under the pan(so pan doesn't get dented).