[Dave at Pelican Parts]

Rocker box == where the rocker arms live, the area you see when you take the valve cover off. There should be a tube sticking up out of there on each head, unless they have been plugged or are 70-71 or 75-76 heads.

The hose near the base is probably for balancing the pressures in the manifolds. It isn't required, but can help smooth out the pulses in the intake a bit.

--DD