cmayna,
I do not know what engine that pump is for but here are a few pieces of (perhaps useless) information:
1. Every 216/235/261 fuel pump that I have seen (on a truck) has had the inlet on one side (to the rear of the engine) and the outlet on the opposite side (towards the front of the engine). Your pump seems to have both the inlet and oulet fittings on the same side of the pump. Of course, one of the fitting might have be realigned.
2. I have seen (and used) dual action pumps (with and without glass bowls) and all have gas inlet to rear and gas outlet to front - with both inlet and outlet on the top half of the unit. The vacuum ports (two) were on the bottom of the unit. These ports were usually (but not always) labelled as "In" and "Out"; and, these ports/holes in the body were tapped the same as the holes for the fuel. Of course, there were adapters in these vacuum ports to fit the smaller diameter vacuum lines.
My uneducated guess is that the pump is not for a Chevy truck with a 216 engine.
A dual-action fuel pump provides a steady vacuum to the wiper motor.
Tim
