Ok 6 cell will be on the same side that the data cable plugs into. Thunder power attempted to be smart and use only 2 plug sizes for their balancing plugs rather than going the way of the crowd and having different numbers of pins in different number of cells. The picture below shows the adapter that you will need,



Here is a close up of the balancer



This is the plug you want to use if you ever use a 5 cell pack



If you want a balance adapter that will work with your 6 cell lipo I could chuck one in the post if you fancy (pm me your address)? I ordered some from hobbyking for a couple quid but they would only send them in batches of 5 so I have an extra few I'll chuck in a 5s one as well in case you need it in the future.