Rear axle housing markings

[WH23G3G]

What does the yellow circle with and X mean on the back of the 8.75 housing? I also had what looked like some white letters on the axle tube and some yellow paint drips on the tube.

[Charger74SE]

What does the yellow circle with and X mean on the back of the 8.75 housing? I also had what looked like some white letters on the axle tube and some yellow paint drips on the tube.

I have the same circle with a diagonal line through it on top of my 8.25 housing. Don't know what that means.
Are there any readible numbers to go with those letters on the axle tube and are they on the drivers side between the u-bolts?
If so, then this is the serial number for that axle that's listed on the fourth row of your broadcast sheet.  (see pics of my axle)

[WH23G3G]

Mine looked like a full X going through it. I thought it was to indicate sure-grip equipped differentials. I had the white numbers on the passenger side axle housing but they weren't readable anymore. It didn't matter, I was just curious what they meant. The rear end came out of some other car, which I don't know what. So I just cleaned up the axle and sprayed it black and painted the yellow mark on the back of the housing, just in case it was suppose to be important in referencing. If I ever want to, the paint I used should come off easy and I can restore the housing like it should be.