[Mgs] OD Query

[frank]

With all the chatter here lately I thought it was an appropriate time to ask a
question I thought I knew the answer to but now am not sure.  I have a od
tranny in a 1971 parts MGB and always assumed that it would not work in my 3
main 1964 B. Yesterday a friend who is a mechanic of sorts told me there is no
problem installing an od tranny from a 71 into a 63 or 64 3 main B.  I always
thought the early 3 main Bs required a different od tranny and that's why they
are so rare and expensive when you locate one. What's the real story?
Frank Krajewski