I have a 2014 with Z51 package and 7 speed manual. Sometimes (not all the time) there is a squealing sound when I downshift from 4-3 and 3-2. It's not a loud squeal, but is obviously enough for me to hear. Also, can't hear it if I'm using the rev matching as the engine blips.

I don't believe it is caused by low differential fluid, as it was supposedly checked as part of the PDI when I bought the car (VIN 1818 delivered 10/15/2013), and topped off at the recent (first) oil change at ~4200 miles (it was 1/2 quart low). The car is not experiencing any problems, and otherwise runs perfectly.

As I mentioned, I don't dear the sound every time I downshift - only sometimes. Anyone else experience this or have ideas what it could be?