This is normally done with the engine gearbox out of the car as i did last year BUT with the right tools is possible in situ.
Read how it’s done at ……. http://diary-of-mgb.blogspot.com/2011/10/that-seals-it.html
Replacing #MGB Rear Gearbox Oil Seal
information about the MGB and MGB GT classic cars including news and reviews, techs and specs – also updates on repairs, servicing and diy modifications I do on my own MGB Roadster
MGB tips mods and maintenance 