When I worked at the Longbridge plant that built Mini's in the 70's in Birmingham, all the steel brackets needing a black coat of paint were dipped into a vat of black enamel hung from steel wires and then after time spend draining over the vat then sent via conveyor through a stove oven. No primer was used, straight black over bare steel. The same process would have been using on these frames and the other brackets, evidenced by the drips on the edges and the witness marks left by the hanging wires. These clues are missing from these by the numbers restorations

so judges take note.