20 to 1 manual steering gear

I bought a 20 to 1 worm and nut assembly to rebuild my large sector manual steering box with. Well it does not fit very well. The teeth on the nut do not mesh with the sector gear smoothly and hit the inside of the case. I got it from a major mopar specific parts house and I'm a bit disappointed. When I compare it to the original nut the new part's teeth are taller and not radiused on the corners. Has anyone else had difficulty installing a 20 to 1 assembly in their box?