ok the 2008 is a very bad buy and has server problems with the 6.4.
The 2009 6.4 Has improved but there is a problem with lack of power
The 2010 6.4 has one major problem that the customers are complaining about and that is it lacks in power this is worse then the 2009 model.
If you can buy a 2009 ford F 450 6.4, this would be the best one to get for the money and least amount of problems for you but does have a lack of power.
I am giving you also the TBS that are on the 2009 for you to review and what to exspect.
I am going to have to send it to you on the next message for you.
Thank you again
Here are the TBS for you on the 2009.