12valve vs. 24 valve

hey guys ive always been a ford guy. i own a 99 powerstroke. i was just wondering what the difference is between the commonrail cummins, the 12 valve cummins, and the 24 valve cummins engines? are there any advantages to either of them or are they all pretty much the same?  

No, there are a lot of differences between the different generations of Cummins. Between the 12 valve and 24 valve are the most dramatic. The early 12-valves are all-mechanical. The 24-valves have electronic injection. There are a lot more differences as well, but those are the biggies.  

the 12 valve is a mechanical injection engine, very reliable and easy to work on. this engine has the P-7100 or P Pump that can be made to put out huge H.P.
the 24 valve has the vp44 pump which is electric and controls fuel delivery. on this engine it is plug and play for more H.P.
the commonrail is an engine where the rail is at very high pressure all of the time
and the injectors are told to open and close by the Engine Control Computer.
this engine is 6.7 L but bogged down with smog control.

12v is the engine to have. 94-98.5
24v has some blocks that crack i think it is #53 or #54 castings. 98.5-2002
Common Rail 6.7 you get sorry MPG because of DPF and added fuel events.  

I have a 2002Cummins, quad cab, 235k 6speed.  I have already replaced the fuel pump and lift pump with an in the tank lift pump.  I have an option to sell my truck and take my grandpa's 1994 cummins 12 valve 97k... any suggestions?  

id get both and p pump your 24v. youd have a better flowing head and better creature comforts but awesome fuel delivery and big power.  
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