How do you change or fix a loose tilt steering column on a 1991 Chevy 1500 truck?

It depends on if it is the column itself, or the steering wheel. The wheel is held on with a bolt, I doubt it loosened, unless it was recently worked on. The column mounts can be loose or damaged( due to an accident). They can be tightened or replaced. With the problem is inside the column, it is needs replacing, with new or 1 from a scrap yard.