7.3 IDI Fuel Mileage?

[CaptainJake]

I just bought a '93 f-250 with the 7.3 IDI. It has an automatic tranny, and 129k. Was wondering what kinda mileage i should expect to get. Ive heard everything from 14 to 22 mpg highway. I intend on driving as efficiently as possible and usually without a load. Also, is there anything relatively simple i can do to this truck to achieve better mpg? I dont know a whole lot about diesels as this is my first. Any help would be majorly appreciated. Thanks, Jake.

[late_99_PSD]

Is it turboed? If so it'll get better mileage then if it doesn't. If not, I would guess around 16-18 mpg, with a snail, closer to the 20 mark, if not over.