I have a 2003 ZR2 S-10 with push button 4 wheel drive when slowing down i hear gears turning coming from the front trany guy couldnt find the problem, thats all it does ,checked u joints wheel bearings ,the only thing i can think of if front end or trans fer help please.  

Make sure Tcase and front axle is disengaging properly in 2wd.  

some times when you go back to 2wd you need to back up a few feet to "unwind" as they say. Check your oil level in the front dif too. I had a 98 Dodge that had a pinion bearing go out in the rear...it sounded like that when you let off.  

make sure its in "2wd" instead of "auto 4hi"

that can do it too.