g 12 1964 crank case crack

[wayne fields]

hi all.
i have noticed a small crack appearing inthe drive side case. just above the ex cam inspection plug to one side of the cylinder stud .has any one experienced this .and if so was it repairable? and what could have been the cause of it.
the studs are 3/8 and new. i notice that it has been welded before. any comments would be appreciated

regards wayne