Do you have any steering geometry issues with the centering and tie rod length?

Is the coupling center line in line with the steering column? Can't really tell from the picture.

A 10 gauge shim is how thick? Where again? Show us

Why are fast ratio arms needed on 16:1 box?

It's difficult for to understand why spending a lot of money on better hardware that doesn't fit without compromise is a wise choice. As far a the firm feel boxes loosening up complaint. Try something called steering sector shaft adjustment. It's in the book [FSM].