[72K5er]

I am working on my '72 K5 and am replacing the master cylinder. It has disc front and drum rear with a proportioning valve. I have reworked the brakes already but I need help with the master cylinder. The mc it came with when I got it has the larger res in the front and the smaller res in the rear. It has a black bendix booster. I ordered a new mc for my application and the one I recieved has 2 reserviors of the same size. From what I have read, this is more common with the bendix booster. Which one should I use? Is there a reason the one has a larger front res? I have attatched pics of both. Thanks for the help.