Got 54k on my truck a lot of snow plowing some towing no tranny problems or lift pump issues

 

Don't worry about when the truck was built, the mpg comparison in small, my 2006 went 2200 miles to canada running 69-70 mph and had an overall mpg of 21.8 hand calculated. So they get fine mileage, also you will notice a very small difference in the pulling power of the two trucks. Just go look at it, if you like it...buy it, it will be a fantastic truck either way. Remember people come on these forums to complain about their problems, and you will hear alot of different problems, BUT this is just a very small portion of cummins owners and alot of guys on here have caused some of there own issues by adding power.