Redline Synthetic is great fluid too. The spill and fill method is bad policy. IPD sells a very simple flush kit that I have used. ($12.50) It consists of a plastic hose and a new clip. Remove the battery. Take off the top hose from the trans cooler at the radiator. Put the IPD hose on the other hose. Start the engine with the emergency brake on. Let a couple of quarts pump out...refill with a couple of quarts...keep this procedure going until the fluid runs clean (into a 5 gallon bucket) It will take about 10 qts to flush it out...it holds about 8 qts. The whole process take about 40 minutes and will cost less than $100. No plugs are removed...just the hose.
You will need a 5 gallon bucket or you will rish an environmental disaster. When done, I put a sheet of plastic over the wate fluid and immediately took it to Jiffy Lube fore disposal.