741, cone sure sure grip, 3.23, 1970. What is it worth?

The value really depends upon how much you actually know about the unit and are willing to put your reputation on as a seller.
If you have actually used the differential and can vouch that the cone sure grip works, the gears and bearings are quite and it is 100% reliable and functional then it has a value in the higher end of what is mentioned above.
However if all you know about the differential is what you can see and what we can see in the photos, then the unit is basically a core and has a value in the lower end of what is listed.
That is how I would look at it as a seller or a buyer.