A 1998 GMC Sierra SL Extended cab 4.3 V6 engine rear wheel drive truck has a 25 US gallon fuel tank.
15.5 gallons
For a 1998 Ford Taurus : ( the gas tank capacity is 16 U.S. gallons )
The gas tank on the 2012 GMC Sierra-2500HD holds 36 gal..
The gas tank on the 2008 GMC Sierra-3500HD holds 34 gal..
The gas tank on the 2010 GMC Sierra-3500HD holds 34 gal..
The gas tank on the 2006 GMC Sierra-2500HD holds 34 gal..
The gas tank on the 2014 GMC Sierra-3500HD holds 36.0 gal..
The gas tank on the 2011 GMC Sierra-1500 holds 26.0 gal..
The gas tank on the 2011 GMC Sierra-2500HD holds 36 gal..
The gas tank on the 2013 GMC Sierra-1500 holds 26.0 gal..
The gas tank on the 2005 GMC Sierra-2500HD holds 34 gal..
The gas tank on the 2011 GMC Sierra-3500HD holds 36 gal..