Drifting or to much play in the steering

1979 cj5 Renegade, 258 with a T150 and dana20, 4 in lift and 33x12.50x15s on 10" rims. I just got my front end rebuilt this last summer, to enclude the powersteering gearbox. The old girl just does not feel right. She drifts on the highway and I am always having to readjust driving at the wheel. It just feels to loose and or is to loose. I want to give it to my son in Tucson at the University of AZ, but not until I can correct this issue. I have adjusted the gearbox twice and it does not fix the issue. What else can I do!