Morris Minor Owners Club

Are there different Diff ratio's on Series MM Morries?
I heard ther was two. And what are they and why the difference?

The standard ratio for a Series MM was 9/41 = 4.55:1
Optional ratios were 7/37 = 5.286:1 and 8/43 = 5.375

The last 2 ratios were usually used on the on the Series II
The axle ratio eg 9/41 should be stamped on the axle casing near the diff