Need Advice Input On A 2001 Hd Duramax

[stillen]

I work for a dealer, and i have the opportunity to purchase a 2001, gmc sierra, 2500HD, extended cab, 4x4 , Duramax... Has 175k on the odometer. It was a trade in, i know nothing about how the Previous owner treated it. My dealer is askig 15k, but looks like i can get it for 12k.... I also have a trade in, in the end, I need to come up with 5k..... I am trading in a 2001, 5.3l gas, 4x4 z71, extended cab with 214k on the odometer.....

 

I love the truck already, its exactly what i want..... I work for a honda/nissan / kia dealer........ so asking the techs here is pointless about diesel trucks....

 

Is there anything i should look for at this diesel?? Says its a 6.6 liter, is that correct??? The trucki have is flawless, i ove it, but i want the tugging power of the diesel, and mention of mileage? i heard 21 mpg....

 

thanks in advance for your help