The information you have is correct. You can change a SK-1000 to an SK-3003 but nothing else due to the smaller motor used in SK-1000. The SK-3000 can receive 101, 110 and 119 but not 99 or 103 where the HD programming is located.
You absolutely can sell your SK-1000 as it is in high demand especially if someone could save a good deal of money. The bases and the cabling for both unit are the same so it would only involve removing the antenna and cabling from the base and installing the new antenna on the existing base. You then take the brand new base you removed from the new SK-SWM3 and install that on the old SK-1000 and the new owner is all ready to go. You also need to change the controller inside the coach as the SWM controller is not compatible with the Dish controller but that's just a matter of unplugging one and plugging the other in.
