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

That's not possible.. I wonder if you can go to the parts house and use universal ubolts in place.. Now if those fit report back with your finding's you sir are a genius.
They say the universal u bolts are round at the op where the bolt contacts the top of the axle tube. This will crush in the tube. That is why it is important to have the right u bolts. From what I have read.