Advice on 05 international 4400 and 02 international 4700

I am new to the forum and trucking world and don't know much about the engines and reliability. Looking to buy a 24 or 26ft box truck and was looking for advise on these 2 models. I am looking at some on the auction. One of them is from usps fleet and i am not sure if their trucks are well maintained. Any advice is appreciated on which engine or truck will be a better choice over the other. I appreciate