Hey Vinnie,
On your 2002 Tahoe you'll have to go with an 'aux input' interface... this will get the audio directly into the system via a T-harness at the back of the radio.... you can't directly control the iPods in GM's until you get into the 2003 model year. You can get a 2003 radio out of another Tahoe or Suburban and put in your '02, then you have full control... only problem is every time you turn on the radio it will display 'cal error' for a few seconds... this is how I have my '02 Olds Bravada set up.
The Lexus is no problem... directlly plug and play with full iPod functionality and control on that one..... go to
www.soundgate.com and you can get everything there.
Yup, I started SoundGate back in '96 and sold it to Kicker in 2006... all of my guys are still there at Kicker doing a great job.... you can also find all the parts you need at
www.logjamelectronics.com ....Logjam has the biggest, and best, selection of interfaces of anyone and the prices are good.
For all you guys looking to mount an iPod, Zune, or whatever in your car, here is the BEST mount I have ever seen.... looks cool, works great...
http://www.logjamelectronics.com/soundm2.html