The tricky winger netted the opening goal as their U23 side lost 4-3 away at Queens Park Rangers in the Professional Development League fixture.
It remains to be seen if anything will come from his latest training spell, but Gribbin will be hoping to follow in the footsteps of fellow former United player Ravel Morrison, who also signed for the Blades following a trial earlier in the summer.
Former United prodigy Morrison starred for Sheffield United in a friendly game against United last week.
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