My 2007 manual states 30,000 miles.
Heres something wierd. I had a 2006 Ram 1500 with the 5.7. The manuals maintenence schedule showed a recommended 7500 mile oil change interval for normal use, and 5000 for severe duty. I now have a 2007 Ram 1500 and the manual states 3000 miles. What the heck? What changed? I always thought that these 3000 mile intervals were a ploy by the quickie oil change shops to make more money unnecessarily.
Heres a tip for changing the plugs if you are doing the work yourself...Prepare yourself for a frustrating time. The rearmost 2 cylinders on both sides are a tough access, but the drivers side is worse with the Brake booster in the way. Dont use too much anti-sieze on the threads of the plugs either. Good luck. The job took me over 2 hours the first time, and I have been wrenching since 1983!