Piston pump gear housing.
If you discover a flat/standard bearing in your pump instead of a tapered bearing on the wobble shaft, you'll need to update this housing when you replace your wobble shaft, seal, and bearings to switch to the replaceable tapered style bearing on the wobble shaft.
Ford: NAA, Jubilee, 500, 600, 700, 800, 900, 2000 4-cylinder, 4000 4-cylinder.