Differential identification!

Howdy people, I'm looking to the rear end gurus here for a little identification of a rear end I picked up in a buy! It is a 741 case, and the gear is a 3:73, but it's the SureGrip unit im in question about! I was told that Randy's set it up, and thinking it's an aftermarket Auburn unit, but I just want to be sure before I use it! Here's a couple pics of each side of the SG unit!!

Any help would be much appreciated!! Thanks all, Geof

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