Info on vintage Stainless Mitra Pac Fab Stainless Filter

[blakeusa]

Can someone tell me which port - lower or upper is the suction and return on this filter.
We are building a portable pump/ vac system using this filter. Thanks in advance.

 

[cowboycasey]

# 30 is coming from the pump and # 3 is going back to the pool from the diagram, I can not find any other info on it...