The case and pinion retainer were painted on all sides (individually) with a shinny (not that flat stuff) looking red oxide color epoxy primer sealer. More red than we often find on the floors of some cars some plants. So things like shims, bolt heads, washers .... were not painted as you might find on some "restored" cars
Each piece was then machined leaving a bare, shinny finish in that areas. The surfaces that were machined depend on what size rear end your car has Seeing that you listed that you have a 69 CJ (thanks) we can provide some guidance and here there
Would rather post pictures of originals but with surface rust and age details are a little harder to make out clearly
With snubber bracket attached - 69 9 inch application
The machined surface in the round balance hole should be more pronounced. Maybe its the angle our I should have brightened it up more
Members - don't copy the paint marks - they likely are not correct for your car and application
Note - Moving this thread to the General Driveline area since the detail applies across the years - 65-73
