The closest you will probably come to finding the 59-60 WP DW with the Gorman-Rupp pump and the black Bakelite wash arm is the top loading portable in the warehouse. In the builtin that design was TOL, but models below that were a funny design put together out of spare parts with the GE's bow tie impeller, a WP top rack and a no sides GE style lower rack that was literally just the lower rack out of a GE roll out DW with added wheels, but with no side rails so you could not load skillets, etc. along the sides unless you did it after the rack was partially back in the machine. I'm not sure you could even stand bowls in the corners; I don't remember if there was nothing to hold them.
After we found the portable, John had a brand new wash arm the he said I should try in the portable. Turns out that the wash arm was for a builtin and turned the opposide direction from the portable's less shiny wash arm and squirted water out the baffle over the water inlet and made piddles on the floor.