The quad cab has a smaller back seat and a larger bed, the crew cab has a larger back seat and a smaller bed. To compare them you can go to http://www.ramtrucks.com/en/2011/ram_150... and select the Build My Own option from the bottom of the page.
Heart muscle thickening (called cardiac hypertrophy) can be a healthy response to exercise and pregnancy; however, it often occurs in people with high blood pressure, diabetes, heart failure and certain genetic conditions.
The main artery from the heart (aorta) becomes thicker, stiffer, and less flexible. This is probably related to changes in the connective tissue of the blood vessel wall. This makes the blood pressure higher and makes the heart work harder, which may lead to thickening of the heart muscle (hypertrophy). The other arteries also thicken and stiffen.