Locking rear diff without trd package

It was a factory option even for the non-TRD trucks, not common but I bet that's what you've got. That's why you sometimes see early model first gens (1995-97) with rear lockers before Toyota introduced the TRD package, which I think came around in 98 or 99? Either that, or someone swapped in an axle from a TRD Tacoma at some point in time

 

I managed to find this article. The vehicle in question is a 4runner but that looks like the same diff locker as in my truck so im guessing someone put it in themself. Hopfully i can test it out soon and let you guys know. I appreciate all the help