The Ram comes with three cab options, a regular cab, a four door Quad Cab, and an extended quad cab called the Mega Cab. Bed lengths are also customizable and can be extended up to 20 inches. The entry-level engine for the Ram is the 3.7-liter overhead-cam V6, rated at 215 horsepower. A 4.7-liter V8 uses modern overhead-cam heads to generate 235 horsepower and the popular 5.7-liter Hemi produces 345 horsepower. At the top end of the scale is the 8.3-liter pushrod V10 in the SRT-10, rated 500 horsepower and 525 pound-feet of torque. A six speed manual transmission is standard on the 3.7-liter V6 or an optional four speed automatic. A five-speed automatic is optional with the 4.7-liter V8 and standard with the 5.7-liter V8 Hemi. The SRT-10 Regular Cab comes only with a six-speed manual gearbox; the SRT-10 Quad Cab comes only with a four-speed automatic.For 2006, the Ram 1500 is completely restyled. The bumper fascia, grille, headlamps, fenders and wheels are all new. Additionally, a new hydroformed frame that boxes the vehicles full length provides more strength than in any previous Ram 1500. The Hemi-equipped Rams feature the new Multi-Displacement System (MDS), which shuts down four of the Hemi's eight cylinders when they are not needed.