I agree Andrew, my suggestion was to try and find a spider gear from someone who installed a locker and just replace it and leave the thing open diff, but he is head strong wanting this mini-spool.

Does anyone have the top spider gear laying around????

 

Ok, I tore into the rearend and this is what I found out.
The axle shafts are 35 spline, it is a 10 bolt cover and the ring gear is 9 1/2".

Does anyone happen to have a set of spider gears for this rearend???

 

35 spline, 10 bolt with a 9 1/2 ring gear... sounds like after market or its not a chevy housing.... Got pictures??? SF 14 bolts had 33 spline axle with a 9 1/2 ring gear... I have one from a 97 Z71 with 6 lugs and I have both an open and gov lock carrier...