Lionel has probably been making the RTR train set 4-4-2 since 1900...
Anyway, I've got the 2004 Pennsylvania Flyer version. It was the set that got me back into O gauge at Christmas 2004. Other than replacing the smoke unit a few times and the whistle motor once, it just keeps going. You'd have a hard time finding a more reliable engine. Mine is just the air whistle version and has a puffer smoke - no electronics. Great engine.
Unless they've changed, which I doubt, they are an absolute nightmare to take apart and especially put back together. It is so bad that if I ever need to open it up, even for a minor tune up I could do in 15 minutes, I have my local dealer/repair man do it. It is that bad IMHO.