If you get the HK600GT, buy an Align head, tail boom, tail block and everything that goes with it, slider, tail shaft and so on. Also get align gears including the tail drive gear and tail shaft. Get an Align belt as well. It will end up costing as much as an Align kit, but if they are not available, this is the next best thing. I had that helicopter and didn't like it, but I never upgraded anything on it. You are going to want a DFC head and the DFC tail block and everything with it. MUCH more control on the tail.