If you are talking about the nozzle receiver, It looks like this. The nozzle tip inserts into this stainless steel plate.
The plate has three studs that stick out from the backside, go thru the side panel and attach the inside nozzle 'tube' to the sheetmetal.
You can see one of the studs/nuts in the 'inside' photo above.
If this is not what you are looking for - and the holes are higher in the side panel . . . then you must have a National A-38-H.
Then the piece you need is a cast white metal, 'U' channel that is 'banana' shaped.
The channel holds the 16' (yes, sixteen foot) hose assembly that went on these pumps. The hose exits from the base of the pump - loops up and over the 'banana' holder and then ends with the nozzle. There is also a hose retainer that mounts to the edge of the side panel about 30" up from the ground.
You can just see the bottom end of the 'banana' piece in the outside photo above.
If you need additional photos of any of these parts - shoot me an e-mail and I'll send some out to you.
Later . . .
Jim