are you talking about the 1/8th" stereo jack input or the USB input jack? the 1/8th" aux in. was available as early as 2008, and i have the single disk AM/FM/XM with that jack in my 08 GT. the USB input didnt come until 09.5 i beleive. i havent had any problems with mine.There's nothing to tighten...it's just a male input jack and it goes in but very loosely. I don't know what the deal is. It's extremely strange.
I'm surprised more people haven't had this issue. Maybe it's only cuz the 09's were the first to have the Mp3 jack or something.