As Ian has highlighted it’s been modified to fit the “ narrow “ gearbox plates / box on the 46/48 B series
That box perhaps wasn’t the greatest being based on a pre war design - so when they eventually started giving bother - military surplus boxes were a plenty & cheap
I should think you could come up with a gearbox case relatively easily in your part of the world....Many of the M20s we lent you weren't sent back...!!:laughing: ...Ian