I just changed the fuel pump on a Silverado 1500 (non-HD) - took about 4 hours, and I'm not really a mechanic by trade. That didn't count the time it took to siphon the gas out of the tank though. One trick I learned is to open the screws holding the filler hose up in the filler hose, then you only need to deal with one clamp holding the hose to the tank. Since I did it myself, it was somewhat of a balancing act getting the tank down and up, but a floor jack helped - wish I had a transmission jack or extra hands to make it easier.
The 2009 Chevrolet Silverado-2500HD is 18 ft. 8.7 in. (224.7 in.) long.
The 2006 Chevrolet Silverado-2500HD is 18 ft. 6.1 in. (222.1 in.) long.
The 2002 Chevrolet Silverado-2500HD is 18 ft. 6.1 in. (222.1 in.) long.
The 2008 Chevrolet Silverado-2500HD is 18 ft. 8.7 in. (224.7 in.) long.
The 2011 Chevrolet Silverado-2500HD is 18 ft. 9 in. (225 in.) long.
The 2010 Chevrolet Silverado-2500HD is 18 ft. 8.7 in. (224.7 in.) long.
The 2014 Chevrolet Silverado-2500HD is 18 ft. 9 in. (225 in.) long.
The 2007 Chevrolet Silverado-2500HD is 18 ft. 8.7 in. (224.7 in.) long.
The 2004 Chevrolet Silverado-2500HD is 18 ft. 6.1 in. (222.1 in.) long.
The 2005 Chevrolet Silverado-2500HD is 18 ft. 6.1 in. (222.1 in.) long.
The 2001 Chevrolet Silverado-2500HD is 18 ft. 6.1 in. (222.1 in.) long.
The 2013 Chevrolet Silverado-2500HD is 18 ft. 9 in. (225 in.) long.