I have searched for high quality AC bearings of the same size and so far not found any that would fit. I do not claim I have made an exhaustive search.
The ISO model number for the standard 3 piece thrust ball bearings is:
51101 and the dimensions are:
My understanding about fit for AC bearings is as follows:
ID - must be absolutely right
OD - must be very, very close to right
Depth - you can easily get away with bearings of lesser width (meaning depth of pocket) as long as your mechanism to tighten (load) fits inside the pocket (high tolerance spacers apparently work). It has been suggested to me that having a bearing marginally too wide (say a 10mm width bearing in a 9mm pocket) would also be OK.
So far, all the "good" (expensive) AC bearings I have found with a 12mm ID are too big in OD which would require machining the diameter of the pocket larger.
If you find any please post your results!