Hard pedal, bad booster?

[chevnut55]

I removed the brake system in my 69 Camaro and replaced it with c5 brakes, I just installed it in my dads 65 el camino with a stock 350.
The stock 65 booster worked fine with 4 wheel dumbs but after installing the master/booster from the 69 the booster does little and the pedal is hard just like it was in the Camaro.

Everything was new from cpp and thought boosters were bad if they leak or do not hold vacuum.



Both cars make enough vacuum psi and everything is stock gm.

What could the problem be?