brake system setup

[SS Shaun]

Ok so i am still working on my brakes and i am having a hard time figuring out why i can bleed my rears. so i was told many things and finding many different answers. so i wanted to know what is the difference between the following

proportion valve? hold off valve?

distribution block?

Proprotion valve built into a distribution block?


now what is the importance of the first picture to the brake system? i ask because i want to a car show with about 5 chevelles in it 69, 71,72,67, and 70 and none of them had it on they all had disc in the front and only one had manual brakes. and the 69 had this in its place


i am thinking of moving mine from the distribution block from the frame to the master cylinder because of my headers. Its in the way and i its very hard to get to. thanks for the advice in advance