Separating an A12 Box

[classicdat]

I have received a question from a Morris Minor owner, and it has been too long for me to remember what it was that caught. any one able to shed some light?


I am a member off the Auc Morris minor club, and am fitting a Datsun 1200
motor and 4 speed box to it l can not get the tail shaft housing off the
box ,i have followed the book, it slides back about 25mm then it appears to
lock on something. Any of your members have any ideas?
Regards
Dave