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.
Hardening and thickening of the heart muscle, known as  hypertrophic cardiomyopathy, is often the result of genetic inheritance, according to MedlinePlus. Defects and mutations in the genes that manage heart muscle growth, while inherited, can manifest differently in severity or symptoms across a family.