For Plunger and Rigid application ONLY, but feel free to chuck in two bob......
A while ago when playing clutch, I did a rear wheel alignment check...and being an advocate of the rear axle should be parallel with the G'box mainshaft, I did some measurements and found that the distance from the mainshaft centre to the rear primary chaincase screw is about almost fairly close to exactly about the same as the distance from the mainshaft to the gearbox rear outer cover screw (but a bit higher)....so I figure it's close enough to use as a check for measuring to the axle for parallel alignment..without pulling too much apart.....??
If anyone is in a situation to be able to verify or dispute this
, I'd be interested in input...just to make things easy for us all