8 3/4 value.
I paid $450 for the bare case with SBP axles,adjuster and backing plates last fall. Then $200 for a Sure Grip unit. A gear set with decent gears (3.55) in a third member and a Sure Grip can go $450 and up too. So, if combined, you could pay a fair price of $900 and up.
You know if it has a Sure Grip if it tries to spin both axles in the same direction at the same time instead of opposite directions (unless the Sure Grip has been fried).