One Hump or Two Hump Master Cylinder

[4spd69RR]

I know, I know may thousand CA. camel fleas attack me.

 

[resq302]

Im almost certain that the two hump was the factory installed style. The bail wire lids were primarily used on disc brake cars since the fluid needed to be added a lot faster than drum brake cars would due to the pistons moving out and the fluid taking up space. I seem to recall that there was some kind of reason behind why they made that different style lid but for the life of me I can't think of it now. Possibly something to do with manual vs power drum brakes?