Can anyone tell by the pics what this is for? And maybe what it's worth

Thanks! -

 

thats a GM factory mechanical locker (G80 in the glove box).... they go for about 100 bucks... good for an everyday driver but not good if you like spinning the tires..... hard to say what ring gear it fits or what spline....

 

Do you know what the interchange is?

Thanks for the help