Does anyone know why a brand new intermediate steering shaft and new bearing would be creaking? It is the flexing between the body and frame causing the creaking sound.
What type of creaking? Is it like a door hinge creak (dull creak) or like when plastic rubs (higher pitched)? Not to question your mechanical ability at all, but was the bearing pushed fully into the column? And did you ensure that the steering wheel did not turn during the job?
I just did the steering bearing and steering shaft replacement on my tahoe earlier this month and getting that bearing on wasn't the easiest thing to do so it was just a thought.
Otherwise, check everything else underneath the vehicle including the easily missed / skipped over components: control arm bushings, torsion bar bracket bushings, differential mount bushings, body mounts, etc.