Not quite true.  The G has "ball joints" at the ends of the drag link (ahead of axle, runnig from steering box to right swivel housing) and the tie rod (behind axle connecting L and R swivel housings).  Wear in those joints can cause just the vibration symptoms mentioned. 

The way to check them is as follows:

1- Jack up the right side wheel off the ground (jack on the radius arm below the axle tube so the wheel iis floating free)

2- With key on to free the steering wheel, have someone move the steering wheel from side to side to the point where the left side wheel (on the ground) tries to turn, but moves only a tiny bit.

3- from under the vehicle, inspect each of the 4 rod end joints to see if the rod moves in relation to the knuckle or pitman arm when the steering wheel motion changes direction.

If there's motion in any of the joints, replace them all.  Easiest way is to just buy two new rod assemblies.  But I think some are offerning the threaded joints alone if you want to replace just the joints.  It's more labor work, but cheaper parts.  Either way you'll need a good alignment when you're done.

Checks for wheel bearing and kingpin play are detailed under a recent post.  Search for "king pin" with me as the author.  Premature wear of these items is caused by a build up of effects of bad caster due to lift, bad alignment, and heavy wheels and tires.  See my recent post about maintianing things correctly to avoid other problems. 

This is a textbook case of why I tell people not to just replace the steering damper as a knee-jerk reaction to steering vibrations.  The steering damper doesn't cause or fix vibrations, it just masks them from the driver's perception.  The forces that cause the vibrations are at work on the components downstream of the damper whether you can feel them or not.  Having a good steering damper in place actually does more harm than good as it applies the resistive force for the wheels to work against to stress all the components between the road and the damper, while masking the vibration from the driver.  When the truck is experiencing vibration in the steering, my standard reply is to first REMOVE the steering damper, then address defective or maladjusted components until the vibration is gone, and then refit the damper (or a new one if the vibes have destroyed the old one as they must have if you could feel them in the steering).

I too can't offer any help on the blower or seat switch issues, but at least those aren't safety related as are the steering and brakes.

Good luck!

-Dave G.