just checked my reference books and they show photos of M10's around the period of 1944 - 45 that have both types of drive sprokets.. the 'lace' and the 'cast' versions some of the photos were from the winter period.. so I think either or would work.. I myself am doing one of these at the moment..
it is my understanding that the 'Lace' version was the early one and the 'cast' came later...
drive sprokets were replaced out of available supplies as they wore out or were damaged which is why you find a mix of both types throughout the war.