sparty can give you no more info. i now have his truck. it is a c1500 with the 4.3 nd the auto trans. it now has 124K miles on it and has no problem towing. i regularly haul trailers filled with gravel, other vehicles and many oats. never had a problem.
my pops has a 96 cheyanne 4X4 with the 4.3 and he just hit 190K. the engines are sound, and as with any engine, proper maintenace does more for the engine than the engine itself does.
with that said, it definately has less power than my vortec 350 did. i havent had any prolems though and dont forsee any. as for plowing, it would be fine for residential, but for comercial plowing, i think you'd want something with a bit more grunt to it.