inner primary cover

were there different types of inner primary cases for the commando? I am concerned about the fit on the motor . there appears to be different size bosses around the crankshaft.

the model in question is the 20M3S model...it looks like a very early set of cases.

I have two sets of cases.......20M3S 148561

.......20M3S 149027

the first one uses the usual commando inner primary, the other looks like it is still using the old tin covers.....but it is a later number. Any ideas?