Anderson
One defining feature of Anderson pumps is the head construction.
They have a brass Valve Plate with the Valve Assemblies screwed on both sides.
The Valve Plate sits above the Head with the liner in and has another dome-like part on the top (valve cover).
This will be held down by Large Brass Nuts. The number of brass nuts will be a great help in identifying.
The 253/402 has one brass nut. This is a small pump.
The 355 also has one, but it is a medium-sized pump.
The 605 has two brass nuts.
The 1105 has six brass nuts.