I have a Savage X4.6 and I was looking to get a Spektrum DX3E Radio. I still have the standard AA battery pack in it now so I plan to upgrade that also. My question is what hump pack do I get? And also do I have to modify anything in order for it to fit? And lastly I just have a cheap Piranha peak power battery charger. Will this charger work for the hump packs? Thanks, Eric