The bars all have two letter names. GK bars will have a tag that says GK on it.
The only difference between the bars is spring rate.
A higher spring rate will be a stiffer srping (or torsion bar) this means that if you "crank" it beyond factory height it will sag less than a light duty bar. It will also ride "smoother" because instead of wallowing around it will be stiffer on the road, especially since cranking totally changes the design angles of the suspension.
All the torsion bars for these model years are the same size EXCEPT the tahoe bars are a couple inches shorter.
Hope this helps.