If you're referring to an advanced design truck, I replaced the shaft on mine due to steering wheel thread damage from previous owner. I got a new shaft from (I think) Jim Carter. There is a weld joint near the bottom of the shaft near the gear. I carefully cut and rewelded the joint. If you weld, be sure to clamp it in exact alignment and let it cool completely before unclamping.
I didn't do anything with outer case, but procedure is the same.
Dave Evans
52_3100