Are all zero stacks the same????
 

My bike came with a CaneCreek zero stack headset but I want to get the CaneCreek 110 zero stack headset to replace the cheap one. What I wonder is if the tolerances or might I say height of these are the same??? In other words, my fork tube will not need any alterations I assume.

As long as you have a decent (maybe 20-30mm) spacer stack to play around with, there should be no steerer tube alterations necessary.