Hi Phil:
What a coincidence, I just fixed mine this past Friday. The tailgate wouldn't open and close. I decided to get both new latches and handle, and I recommend you do the same. It's a lot easier to fix and will work great again. It's a simple fix. My handle was rusted completely up and wouldn't work.
Both of the latches were in stock at my local dealer for ~ $34 a peice. The handle had to be ordered and cost ~ $90. It's not cheap but that's what you gotta do. Also, I ordered 3 new tailgate handle screws. It requires a # 4 phillips head screwdriver. Save yourself a lot of grief and get one of these before, I stripped one out and had to grind it off.
Here are the part #'s off of my receipt, pretty sure these are correct:
55275484-A Tailgate Latch
55275485-A Tailgate Latch
55074662 Tailgate Handle
Hope this helps!