Hummertech,
2004s have 2 different type amps, and the part number of TNR you need depends on which type amp your truck has installed. This was a mid-year change.
The Bose amps were changed in mid 2004 to a lower grade model. 2003s have the "LUX" amp, just like the Cadillac Escalades. The later 2004s and the 2005s have the "premium" Bose system. You can tell the difference my the audio selections available on your radio. If your audio selections include "Normal, Driver, Rear, and Spacious" you have the "LUX" amp. If your selections include "Custom" and "Talk" you have the "premium" amp.
The part numbers kept changing, so I'll have to do a little searching to see what folks say are the latest GM part numbers.
Check out the Avalanche forum. That's where I get quite a lot of info.
http://www.chevyavalanchefanclub.com...ard,157.0.html