On my 87 Blazer, it has the 2 piece rear opening. Top window opens upward, bottom tail-gate comes down. And at the top of the tail-gate, there is a little black turn **** with 2 arms stinking out, and a key hole in the middle. A couple months ago it worked fine. You put the key in, and turn the black part left, it opens the window, then right helps drop down the tail-gate. Well now, the black part just spins around and doesnt "grab" the key hole like it should. Anyone have/had this problem and know how to fix it?

 

You have to open up the gate & see the mechanism. Sounds like it's broken & you should be able to find a new one on rockauto.com. Don't forget to look in the main page here for the monthly discount code.

 

Mine did the same thing once when I turned it too hard one time and "overshot" the internal catch lever thing. I had to remove the inside plastic door panel and some other metal shields to get to the inside of the latch to re-engage the little lever that the black twisty handle engages with.
Does that make any sense?
It is possible however that you simply broke the twisty handle and will need a new one.
Sh*t happens, and nothing lasts forever.
Rock Auto is your best bet for a new one.
GOOD LUCK!

 

Any parts store should have it. I replaced all the outside locks in my 87 years back and got them from autozone (before my personal boycott of them).