I found an article on the 4.7 just some food for thought.
Chrysler’s first truly new V-8 since the 1960s, the Next Generation 4.7 (briefly dubbed “Corsair”) had better power, gas mileage, and emissions than the 318 V8 it replaced; a new truckV6, the 3.7, was based on it, as well. The engine was reportedly designed as a replacement for the 4-liter AMC I-6, with the 3.7 to replace the AMC 2.5. According to Bob Sheaves, the concept originated at AMC, before the company joined Chrysler.
EGR and knock sensors were added in 2005. In model year 2008, Chrysler replaced the 4.7 liter V8 with a new version. Power went from 230 hp to 290 hp (and up to 320 lb-feet of torque) with that move; gas mileage went up, and noise and vibration went down. The new 4.7-liter V-8 features 5.7-Hemi features such as two spark plugs per cylinder, with a high 9.8:1 compression ratio, and better port flow; but it has a new slant/squish combustion system design.
Refinements included significant revisions to the induction system, reduced reciprocating mass via a lightweight piston/rod assembly, and reduced accessory drive speed. A new normally open valve lash adjuster system smooths the engine at idle, while electronic throttle control is needed for new stability systems. The engine will be manufactured at the Mack Avenue Engine Complex in Detroit.
Production is slated to end in July 2013, according to “pgcooldad,” a date which corresponds to other sources. No plans have been raised for the plant itself; the 3.7 V6 equipment will move to Trenton in summer 2012. He wrote, “I believe that dealers want the 4.7L because they can offer the customer an upgrade, the Hemi. Once the Hemi is the base engine it no longer becomes ‘premium.’” The 3.6 V6 produces around the same horsepower, but falls around 60 lb-ft of torque short, an issue for trucks.