Normally I don't recommend for or against transmission flushes but in this case it might be a good idea to have that professionally done. You will only get about four quarts out with a filter and fluid change. Another four or five quarts hangs up in the torque converter, clutch packs, and other passages that will only be removed with a flushing machine. Antifreeze doesn't have the lubricating properties of engine oil and transmission fluid but more importantly when antifreeze gets into engine oil it will melt the soft first layer of the engine bearings leading to catastrophic failure. Automatic transmissions have drums that rotate on similar bearings so logic would dictate they could suffer the same fate.
The cooling system is not as critical but you do want to flush the system. Engine oil and transmission fluid will rot the rubber radiator and heater hoses from the inside. They will look fine from the outside but you'll never know when one will pop a leak. I would drain as much as possible then remove one heater hose from the engine and run water from a garden hose into the hose and the port to flush the heater core. That will wash through the engine block too and flush that out. I like to remove the rubber hose for the reservoir from the radiator and let it hang down. Fill the reservoir and force water to run out the hose. It will siphon itself almost empty that way. When you refill the system there is going to be some water left in the engine and heater core that you can't get out so you'll need to put in more antifreeze than water to get a 50/50 mix. After running the engine long enough to warm it up, the coolant will be mixed and you can take a reading for the freeze point. Then you'll know if you need to add more water or more antifreeze, and since the reservoir will still be empty you'll have a place to put it.
Thursday, April 4th, 2013 AT 2:49 AM