My Blazer is not going fully into 2wd it's grinding so checked actuator and it has vaccum on it all the time unhook it and plugged the line now it is in 2w no grinding so is the switch on the transfer case or on the piece that the actuator cable goes into I don't see one on the transfer case.

 

The switch on the transfer case is a pretty common problem with these vehicles. Luckily it is a cheap part ($15-20) As for the location, it is on top of the case near where the front drive shaft comes out of the t-case. Ease depends on if you have a ZR2 or not. I've been told that if you ahve a ZR2 you can get a deep well socket on it. I do not have a ZR2 so I had to use a wrench. Make sure when you pull the vacuum lines off it, make sure you pay attention tow here the little pin is so you get the hoses back on in the right way.