WIW - 7-1/4 sure grip

I'm curious about this as well. As I understand it, they are REALLY rare and they go a long way towards helping a 7 1/4" axle live. The tiny spider/bevel gears in the open carrier 7 1/4" axles are a weak link when doing burnouts in one wheel peel.
Just as it is with transmissions, it isn't always the speed of the parts moving that kills them, it is the sudden shock of gaining traction and the built up momentum of the parts slowing down so quickly.....For instance, peeling out in dirt then crossing over to the pavement where the wheelspin sometimes rapidly slows down.
I scoffed at a guy selling a 7 1/4" SG axle a couple of years ago but as is so often the case with me, I later realized that what I thought wasn't always right! These are rare and have value to some people. I could see a person with a small bolt pattern car that didn't need the weight or durability of an 8 3/4 or couldn't afford one...This could be pretty cool for those people.
My guess as to the value of a 7 1/4" Sure Grip differential? $200 if rebuildable, more if it is in good, working condition.