3 Piece Crank question

Hello all,  I need a set of 3 piece cranks for a CCM Flyte I am putting together (just have a bare frame and forks). Have a question though....  were all of the crank sets used the same size?  (as in bearing diameter etc.) or, were there different sizes used depending on year or series?  Someone told me that they used several different sizes but I can't confirm. Could really use some help from the experts :)   Thanks in advance....