Anyone know what these numbers mean on my diff cover?

[1989 R3500]

I'm guessing that the last set is the date of manufacture. But the rest have me wondering.

The only thing I can find is the 30809 number is obsolete, but it doesn't have which rear end it fits.
Thanks in advance.

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[Nonstop]

Looks like it is off an 85-89 P300 UPS chassis with a 70HD. Thanks Billavista! Basically, it should fit most 60’s or 70’s.