Killed the double pole breaker and none of the other breakers went
If it were a split buss panel, you would undoubtedly have more than a single
double pole breaker
It is entirely possible that the service was installed improperly,
especially if the meter equipment and panel are of a mid 60's vintage
I will try to anticipate your next question.
No, I will not send you the box because you don't believe it's not a
split bus panel. :-)