Newer plastic style master cylinder

i got mine with my brake booster

http://www.resto-modtechnology.com/servlet/the-2132/63-dsh-74-MOPAR-%7C-CHRYSLER/Detail

im not happy with mine, one of the caps leak a lot and i tried to put some cardboard inbetween the cap and the rubber seal, but that didnt help.:/ im goin to start looking for a new cap