In the 60s and 70s, there was a lot of crossover between automotive and piston aircraft parts. In particular, Cessna used the same voltage regulator as Ford. Ford used millions of these and Cessna tens of thousands. They were all made on the exact same production line and all got a Ford part number.
Relying on statistical process control, Ford demanded a certain percentage of their parts get extra, manual QC inspection. Cessna demanded 100% inspection of their parts.
Solution: make all the parts on the same line, divert enough for the greater of (Cessna production plus spares) or (Ford’s SPC needs), QC that amount and stamp those inspected parts with a Cessna number (in addition to the Ford part number).
Ford and Cessna can each get parts cheaper than if they were handled separately.
Now, the question comes up: if there are no QC failures detected, are the Ford-only parts as safe as the Ford-or-Cessna parts coming off the line?