Nice job Marcus
I have only found bare steel preserved under the grease and grime. At the very least the bare steel would seem to be the more typical.
+1 as mentioned in a number of prior threads
Noticed on page 3 the following
"Typically the top cover has a LM stamping on it and could have been hand marked with
either the transmission code or the last few digits of the VIN to help match to the car during assembly."
Have you found some that did match the VIN? If so do all of the examples follow that pattern? Maybe just a coincidence, like when the last three of the VIN match the assigned rotation number.
Something to consider - if it were the last three digits that would be the only example that I know of where they used that practice since all the other identification was to the rotation number and something we see on some San Jose installed engine and transmission assemblies. Also on the line the rotation number rather than VIN is more noticeable since its written on the body to be seen at a distance on located in an easy to find location on built sheets as well as many years and plants written largely on the bottom half of the page to stand out
Just thought it would be worth mentioning