I just went to this one shop and they're trying to BS me that the crutchfield kit wouldn't be enough because I need some kind of Interface Adaptor to add 2 RCA inputs to my stock stereo, because the new aftermarket deck would sit below the original and connect to AUX. Now I'm thinking crutchfield is not that stupid to send me a kit that would require another adaptor (which btw costs $99). Who's legit here and who's BSing me?

Thanks guys.