Dave Wise(MMC Detroit)and I have been working on "beefing-up" the alternator section in his new Dodge judging manual. Like Scott said above the pre 70 cases are uniquely marked and varied. For example, we see at least three different case bolt head types. Clear zinc w/no pattern like the type on the hemi unit above, clear zink with a "bullseye" pattern - more common on 70-71s, and black phosphate coated with AF stamped indented head. The only consistent marking Dixie has noted on the production line rear shells is a small black ink? mark again as seen on the NOS unit above. Ocasionally, we find some random red ink? locatd on or near the rear pivot eye. We have also noted red paint on a couple of the 37 amp rotor stems. This can be seen looking through the pulley throat. Again, agreeing with Scott, we only replace the paint/ink marks on a customer's alternator if we have found evidence that it was there before cleaning.