This reminded me of this old video about Burgmaster. Turns out they seem to have got their castings from local foundries, so not in house. I believe this is in Los Angeles, which must have had quite a few foundries around in those days.
When I went to work at Garrett AiResearch in Torrance CA in the '80s, they had both an iron and aluminum foundry for casting turbine housings and compressor wheels, respectively. Both long gone now.. Much later, when I was providing engineering support to supplier quality, no type of vendor had worse delivery or quality control than the casting suppliers. All the old hands died or retired and little new blood went into foundry work.
Columbia steel is up for auction on bidspotter right now - Another one bites the dust. We are so screwed! I swear the exodus of manufacturing will really come back to bite the USA in the ass and I think it will happen VERY soon.
It's not just the industrial capacity leaving that scares me. It's the transportation capacity.... the railroads are pulling up yards, removing redundancy (thus removing future capacity), removing spurs and industrial track.