I own a 2011 GMC Sierra 1500, it runs fine, transmission has been starting to slip a little here and there as it has 367 000 kms on it.... Within the last couple of months, my transmission (I think) has been making a ticking noise when accelerating or downshifting in the lower gears, it only happens when going slow and when you first start to accelerate or when you are almost coming to a stop. It also has been starting to tick when I put it into drive or reverse. It is not the u-joints as I have already changed them out because I figured that was the issue. If someone could please help me, it would be much appreciated!