U Bolts from a Dakota rear end working on an 8 3/4. Has anyone used this or heard of this.

As long as the Dak has a 8 1/4 or 9 1/4 rear, there's no reason they shouldn't work. Like Icetech said- the bolts don't care what they came off of, just so the tube diameter is correct. Just may be a little long, especially if coming off a 4x4. Beware the 4 cyl. Daks, they had 7 1/4 rears and the wrong axle tube diameter.