Regarding the bearings in the lightweight diffs, I had to dremel some of the material out of the diff housing because the bearings that came with the original TC3 kit are slightly thicker and do not allow you to tighten the diff all the way. If you found bearings that drop right in, then good for you and no dremelling necessary.
Regarding those looking for fans, my LHS has a Reedy TC3 motor clip-on heatsink with a fan mounted onto it. You can also buy replacement fans with the part number listed in the instructions. Sorry, I don't have the part number, but I do know that it is there because the owner and I were wondering how to get low voltage fans at that size.