jason sanders, freetown, IN, 1970 Dodge Coronet 318

Hello, recently, while out looking for parts in some old scrap yards. I found a 8.75" rear in a huge pile of rear ends. It is all still together -- not cracked open yet. The tag says 2.76 and it spins just like it's Sure Grip when I turn it. I've never seen any 2.76 SGs, but I'm no expert. Do you think this is possibly a Sure Grip or do you think it's something someone welded for a derby car or something? P.S., I can't open it until I buy it and it's a 742 case, I don't remember the yoke size.