I am planning to buy a 1995-1999 Ford E series passenger van with Diesel engine. I was offered a 7.3, 6.4 and 6.0 engine. I want to know which has a more reliable engine and what is the fuel consumption?

How can you be "offered" a choice of three motors? Is this a van that someone is installing a diesel in? The only diesel Ford had in those days was the 7.3L IH built diesel. It was the best diesel Ford has ever sold. The 6.0L diesel was introduced about 2002 and was problem plagued.