[kaisen]

1992 was the first year of the bodystyle
1995 was the first year of the new dash and interior (airbag), but still throttle-body injected (TBI)
1996 was the first year of the Vortec (port injection) and OBD-II
1999 was the last year of the bodystyle

So, finding a 1996-1999 would be preferable.
A 3/4 ton (2500) Sub would give you bigger brakes, heavier duty (E-load) tires, full-floating rear differential, bigger ring gear, heavier-duty bearings, heavier duty transmission.....
But, if you can find one with 3.73 gearing you won't give up much in fuel economy or real world driveability

If you are towing, the 3/4 is the cat's meow. If you're using it as a car, it doesn't matter