A fuel tank for a vehicle, comprising: a tank body having an upper wall, a lower wall, and side walls between the upper and lower walls (14, 16) and defining an interior in which fuel is stored; a plurality of fuel system components disposed in the interior of the tank body and including at least one of a rollover valve (26, 30), a fuel level vent valve, a fuel tank isolation valve, or a fuel level indicator; and an endoskeleton to reinforce the tank body, baffle fuel in the tank body, and carry the plurality of fuel system components in the tank body, and including: a plurality of at least partially hollow columns to support the plurality of fuel system components, characterized by a plurality of spaced apart generally horizontally extending first and second beams (50a, 50b, 52a, 52b, 52c) being staggered with respect to one another such that the first beams (50a, 50b) are not directly above the second beams (52a, 52b, 52c), and having tank contact portions (250a, 250b, 252a-252c, 262-266, 350a, 350b, 352a-352e) attached to the upper and lower walls (14, 16) of the body, and a plurality of obtusely angled walls extending between adjacent first and second beams (50a, 50b, 52a, 52b, 52c) to baffle fuel and to yieldably restrain movement of the upper and lower walls (14, 16). a tank body having an upper wall, a lower wall, and side walls between the upper and lower walls (14, 16) and defining an interior in which fuel is stored; a plurality of fuel system components disposed in the interior of the tank body and including at least one of a rollover valve (26, 30), a fuel level vent valve, a fuel tank isolation valve, or a fuel level indicator; and an endoskeleton to reinforce the tank body, baffle fuel in the tank body, and carry the plurality of fuel system components in the tank body, and including: a plurality of at least partially hollow columns to support the plurality of fuel system components, characterized by a plurality of spaced apart generally horizontally extending first and second beams (50a, 50b, 52a, 52b, 52c) being staggered with respect to one another such that the first beams (50a, 50b) are not directly above the second beams (52a, 52b, 52c), and having tank contact portions (250a, 250b, 252a-252c, 262-266, 350a, 350b, 352a-352e) attached to the upper and lower walls (14, 16) of the body, and a plurality of obtusely angled walls extending between adjacent first and second beams (50a, 50b, 52a, 52b, 52c) to baffle fuel and to yieldably restrain movement of the upper and lower walls (14, 16). a plurality of at least partially hollow columns to support the plurality of fuel system components, characterized by a plurality of spaced apart generally horizontally extending first and second beams (50a, 50b, 52a, 52b, 52c) being staggered with respect to one another such that the first beams (50a, 50b) are not directly above the second beams (52a, 52b, 52c), and having tank contact portions (250a, 250b, 252a-252c, 262-266, 350a, 350b, 352a-352e) attached to the upper and lower walls (14, 16) of the body, and a plurality of obtusely angled walls extending between adjacent first and second beams (50a, 50b, 52a, 52b, 52c) to baffle fuel and to yieldably restrain movement of the upper and lower walls (14, 16).