converting to power brake booster - 75 c10

[tard01]

75 c10 pickup

so i was wanting to install a brake booster. first thing i notice is that the input of the brake booster that goes to the brake pedal itself seems to be significantly shorter than the rod used for the master cylinder.

is there a different way of mounting? is there a bracket/adapter i dont have?

i'm also not sure if i have a jb3 or jb5 brake system. is this dependant on the master cylinder, or all of hte components? was told to look on glovebox, but my glove box has nothing on it (i had it pulled out for clean up today).

appreciate any mistakes people might be able to spare me from =P
(i replaced the master cylinder a few weeks ago)