I brought Kelsey up because they were situated very close to Budd in Detroit. Used to be, back in the old days, EVERYTHING to do with automotive was here in Detroit and in the Great Lakes region. Small stamping plants were sub-contracted to make parts, like Continental hoods, for a larger stamping company. Then, they were shipped directly to Wixom. Ford stamping plants would bid on a part, with all the independent stamping plants. The assembly process is real important, but those parts came from somewhere else and they had to be right.
Kelsey made castings, like brake drums w/hubs, by the millions. Then they machined, assembled studs and races, and washed their parts, ready to accept precision bearings. Remember, one car per minute means five wheels per minute, 20 lug nuts per minute, etc. Ford put out 432 cars per shift in an eight-hour day. Two shifts means 17,280 lug nuts, just in one day! Production numbers are staggering. These parts suppliers did a great job and Ford rarely ran out of parts on the line.