I have a 97 Z71 350 with push button 4WD. When I shift into 4 Hi(or lo) I hear it shift but I don't think it locked the front diff in. My friends told me that it was a solenoid or acuator in the front diff that is out. I can't seem to find the exact part I'm looking for. The Chevy house didn't really know what I was talking about either. Can anyone tell me the exact name I'm looking for, or where to find them. Sorry for the long post and thanks.