Just thought I'd add some help for anyone who's changing their power antenna mast and has a broken gear strip, as this thread had helped me already.
I was getting the grinding sound like the plastic gear strip was stripped, so I took off the chrome "nut" off of the antenna and pulled my antenna. The gear strip looked worn down, so I figured that all I needed was a new antenna.
The dealers didn't have just the antenna anymore, and neither did O'Reilly's and Autozone. Autozone tried giving me a "universal" antenna which didn't fit. So I found a T100 one for $26 shipped on Ebay.
This one is pretty much identical to what I had (good sign), so I tried just slipping in the strip (teeth forward), but this still gave me some grinding and it didn't retract all the way. Must be a broken strip, so I compared with my old one. Sure enough, the strip on the new one was MUCH longer.
I removed the screws on the plastic wheel well edge with a 10mm socket. The other clips came out with a screwdriver. Here's the tricky one that is mentioned in a previous post:
It's circular on the outside with nothing in the middle; pry it up from the edges and slip your needle nose pliers underneath. Note that the tabs are on two opposing corners, so squeeze it tight on the corners, not the flat, and pry it out.
You don't need to remove the entire plastic strip, just enough to get to the antenna assembly. I removed the screws and clips to about the mid-point of the wheel well and that was enough for me to get behind it.
You'll see a few bolts inside, but there's only one, the closest, holding it into the mounting bracket inside. In this picture of the removed assembly, it's the bolt on the bottom of the picture.
Now it's pretty straightfoward. You'll probably disconnect the power harness and it'll pull straight out enough for you to work on it. Remove 4 corner screws and one bolt in the middle. Note that the middle bolt has a nut on the reverse side, so don't lose track of it.
Open up and remove the broken track and you're set. Put everything back in, and you can mount the new antenna.
Total time should be 45 minutes or less for first timers. I didn't need to remove the tire or even jack the truck, though stock 2WDs may not have enough clearance to do this without jacking.