Yeah, and 5.5K is even a stretch. It's completely fine on a beautifull spring day with the sun shinning and the birds chirping, and you are just moving something across town or what not. I've done that before, pulled 8K numerous times with my K5, but in perfect conditions.
People forget that weather conditions can drastically drop what you can safely tow, so if you are in rain, snow, ice, and/high wind than that number can drop to 2/3 of what it is on that nice calm day.
In general, K5's are bad tow rigs, but I will say there are a few things that go nice behind them. A boat, like a bass boat and under 18' or so, 2 place snowmobile trailers, jet skis, small landscape trailers, etc.
It's the longer trailers that can push around a K5, like flat beds and especially longer enclosed van trailers that can catch the wind, they are almost the worst.
Like Rene said, 4.10 gears would REALLY help power, weight distribution hitch, and a good trans cooler if you don't already have one. I'd also reccommend a set of junk yard 3/4ton axles so you can get better brakes, plus your 4.10 gears at the same time. Regardless, you can't do anything about the short wheelbase which is the biggest downfall.
What are you towing?
