Morris Minor Owners Club

Yes the 3.7 comes from either the Wolseley 1500 or Riley 1.5 and the 3.9 comes from the 1275cc Midget but I thought the 1500 Midget used a Triumph axle similar to the Marina one.

Doubt it - it always retained the 4" pcd wheels which means the normal Spridget hubs/half-shafts and drums.

Indeed - The 1500 engine and box is Triumph, the steering rack is Triumph (although was fitted from around 71, pre Triumph and rubber bumpers), but the back axle/ diff isn't. The later halfshafts are supposed to be stronger too (to cope with the torque of the Triumph lump I suppose), but in terms of Minor usefulness the 3.7 diff is the same fitment and drops straight in.

Of course, Midget people know this so there's not exactly a surplus of late 1500 diffs going cheap, but it's always worth keeping an eye out for a complete axle off a scrapper just in case