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 heart undergoes a number of changes during the normal aging process: The heart walls, particularly the left ventricle, get thicker. The heart rate may change. Heart muscle cells may deteriorate. Abnormal heart rhythms (arrhythmias) become more common. Heart valves may thicken or leak.