Detroit locker grinding noise when shifting

I just pulled the rear driveshaft again to prove I’m not crazy and the problem is completely gone
 
Update on this I put redline MT90 in and changed shifting style a little bit and no grinding. Made me feel better to see Jerry had same problem with the Detroit so I’m not crazy. Just have to shift into 3rd at slightly higher rpm and shift into 4th a little slower and all is good.

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