I have done alot of reading and I am confused?????? Can I install a lux amp out of a hummer.........escalade..etc..by just taking the old one out and plugging the new one in??????????????

Yes it will plug in, BUT you have to move some of the wires around in the plug.

And the Hummers stopped using the lux amp in mid year 04, they went to the premuim amps like in our trucks.

What DD said. You will also need a head unit that works with the lux amp. The part numbers are found in smshiver's Do-it-yourself thread, in the first link.

Tom