I'm about to send my injectors out for cleaning. There's obviously two sets. One for primary and one for secondary. Both sets have their own part numbers on them. One set says TL01 BBE and the other TL03 BBE. The place that's cleaning them uses a sonic pulse system that will unintentionally take the paint off the housing once completed. The identification marks will be gone and I don't want to mix them up. I was just wondering what the difference between the two are since they are the same exact physical size. Is there also a method of marking them that will survive the cleaning? Maybe I should etch something into them?