I have a 1956 A7 S/A model with the fully enclosed chaincase. I had to remove the spacer because it was putting to much stress on the rear chaincase with the spacer fitted, the rear of the chaincase was pressing against the rear frame mounting and when tightening the crankcase bolts you were in effect trying to bend the casing. Removing the spacer I then had a slight gap between the casing and the rear frame mount which I filled with a suitable washer. It would have made no difference if a chaincase was fitted or not, I know the front section of the enclosed chaincase bolts to the rear of the rear chaincase using the sliding plate bolts and that is the only difference in fitting a fully enclosed chaincase you have longer bolts for the sliding plate.