Problem Resolved!
Well, it took a while, but it's working now. I tried all the suggestions posted here and elsewhere to no avail...
I resent the activiation signal from Sirius.com numerous times and no success. I was just about ready to take the truck in to the dealer

and decided I'd give Sirius one more call. The guy at Sirius resent the activation numerous times, but the radio would not update. He had me go through a sequence of things: 1) turn off radio; 2) turn off vehicle; 3) remove key; 4) open door and leave open for 30 seconds; 5) reverse the process...
After all this, the radio still would not update. He then asked me to identify the radio's ESN. This is done by turning the radio off, and pushing the "Time" and "Load" buttons simultaneously for three seconds. The 12-digit ESN showed up on the display. After this we tried to resend the activation signal. Five minutes later, no luck.
He then tried to remove or cancel my ESN number. The audio went off. nada. zilch. I thought, "now you've done it. " After this, he sent the same number from the SAT. My radio flashed "updating" for about 1/2 second and the audio came back on. Hmmmm... At least my radio had some function.
After this, he then resent the activiation signal again. This time, it updated and all channels are back to normal.
The guy was very bright, courteous, and knew what he was doing. It took about 40 minutes on the phone to get this done, but he never gave up, and kept trying new things until the problem was solved. My hat's off to him for "staying hooked" long enough to get to the bottom of this problem.