Front & Rear Limited Slip?

[yfs200p]

I did a search after seeing these stickers on the back of the cab that came on my project truck, and found out that it was an option to have a posi front axle. I know the limited slip warning was commonly found on these trucks but i was wondering if anyone has seen one for the front like this. Did they make them from the factory like this? Of course my truck came without a glove box door (therefore no SPID) so i cant check to see if it was an option. The truck seemed pretty original other than the paint and some custom interior touches. The labels are exactly the same except the front one was edited to say "front" with red X's. Anyone else come across this? or was this just a sweet custom touch done by the PO?