Originally Posted by TurboDiesel

Finally, be sure that it doesn't have the infamous "53" engine block. (If you don't know about them, you probably shouldn't be buying a Cummins powered Dodge pickup.) The 53 5.9L engine blocks are well known to crack and leak coolant, leading to necessary engine replacement which is NOT cheap! They can be randomly found in many Dodge diesel trucks, typically from 1997 to 2002. Believe me, you don't want one of those unless you want to change an engine to the tune of $3,000 - $5,000 depending on where you obtain your replacement Cummins and what your overhead costs plus labor is going to cost you. The block numbers are cast into the engine block, near the left front of the engine (driver's side), below the power steering pump area and just above the oil pan mounting surface. They are usually a little difficult to see, and are sometimes covered in goop and road grime attracted by and from the engine crankcase breather / oil spewer.

All the best.