Mine weren't rusty but in the summertime sometimes didn't unlock/lock. Separate issue there though I think that's more of an issue with the little thermal overload on the motors. But all four of mine were pretty nasty inside, dust finds it's way in there. And you pretty much have to break them open to get inside.
But they aren't hard to replace, there's one additional rod on the driver's door but same procedure for all four (my experience is a Supercrew); remove inner door panel (2 little like 5mm screws at base, pry square plastic up to find like 6mm screw under door grab, pry plastic from behind inner door handle to find one more 6mm-ish screw), lift straight up (has hooks on back not those ******* plastic retainers), disconnect electrical connectors for door locks/windows, disconnect cable to door handle by depressing tabs on both sides of blue plastic retainer. Disconnect that red plastic rod retainer in pic above (pry it open with a small flatblade screwdriver). Unplug the electrical connector. Remove 3 Torx bolts on door jamb (T40?). You can fish the latch out of there if you hold your mouth just right and/or monkey with it long enough.
It's a little easier to just remove the exterior door latch (two nuts on the inside, I think one more under those black round plastic plugs on the door jamb), and lift the latch up and out of the exterior door latch hole. In that case you wouldn't have to disconnect that little red rod retainer.
Did mine here and there over the last few months, it's a good time to install Jimmi Jammers and Dynamat/Kilmat/sound deadening while you're in there. I wound up not replacing but opening mine up and cleaning/regreasing, but even if you didn't break them open you can do a pretty good job just cleaning them and hosing them down with a light oil and they will go back to working for a while (I think much of this depends on how dusty it is where you're driving, the worst of the crud collects at the latch part that you already freed up). Anyway good luck!
