Tapatalk is being removed immediately. There are security issues and there is no justification for having it anymore. I apolgize to those die-hard Tapatalk users but you'll need to start using the forums mobile version instead.
I always thought it was little bit later ca. 76', because M10x60 came with newer style side-loader differential (according to bmw parts catalogue later e12 & early e24), where inner crown of differential mechanism was on 10x bolts & diff side half-shafts didn't required bolting to the case.