2000 Tahoe LT Radio Question

[Firewolf]

Y'all please bare with me, some of this may be basic. I just purchased a 2000 Tahoe LT, w/ Onstar, Non-Bose, w/ factory sub. All I get out of all speakers is treble, so I'm guessing either all the speakers are shot, and/or the head unit is shot. My main question is this: I was told the keyless entry and alarm run through the radio, so I need an adapter of some sort to interface with the alarm/keyless entry. Does anybody know what this adapter or interface is called, and if I truly need it? 2nd: I dont know if I have an OE external amp for the sub, and if so, where its at. I saw a reference to a low profile kicker sub on here, was also looking at a rockford and JL subs. Any recommendations?
Again, Im sorry if this is basic. Im learning more about Tahoes every day. By the way, I decided to trade my Jeep WJ in for a Tahoe. So far Im very pleased. Thanks in advance for any and all input y'all....


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