Whats the difference between a 12 valve and 24 valve.... also whats the deal with inline 6?

12-valve 5.9 is the best engine ever. I have two. Get the injection pump replaced every quarter-million miles, and always have the fuel filter changed when the oil is changed, and it'll last forever. Maybe even twice forever.

24-valve engine might be good, too, but I don't need one yet because the 12-valve ones are still running.

I met a fellow a few weeks ago who looked at my D250, and said, "I had one of those but I sold it." I said, "What did you do a stupid thing like that for?" He said, "I don't know. I wish I had it back."