The rack rotates with not a whole lot of effort. Easiest with a deepwell socket and extension slipped over the input spline. As the input shaft tilts aft the distance between the two universals get smaller and you'll have to shave the double-d shaft.
Welding the lower double-d should be fine. I'd skip the upper due to the chance the vibration damper could melt.
I won't be welding mine as I have a heim bearing support in the center.
