Here's a couple of pictures from the 1947-54 Chevy FAM with the diagram of the RPO 340 Fuel & Vacuum Pump instructions. Overall and close up. The pictured pump in this diagram is a slightly different design from your AC 9803, but the number of ports and purposes remain the same.
BTW - The unthreaded hole in the vacuum pump housing is a blind (closed) hole in the casting which isn't used in your application.
~ Dan 1951 Chevy 3 window 3100 Follow this story in the DITY Gallery "My Grandpa Carl's Truck and How it Became Mine" 1966 Chevelle (Wife's Hot Rod) | 2013 Chevy Silverado (Current daily driver) US Army MSG Retired (1977-1998) | Com Fac Maint Lead Tech Retired (1998-2021)
