Re: wanting info on what year 7.3 van to buy and why
My years may be off a little bit... but they are close:
Ford introduced the 6.9 IDI diesel in 1983 and I believe it was offered until 1988 at which time the 7.3 IDI replaced it. A few upgrades were made to the 7.3 such as head bolt size and stronger rockers, but it essentially is a bored out 6.9. The fact that it is bored out means that it has fairly thin cylinder walls and more prone to cavitation or 'block worm' than the 6.9 was. In 1993 and 1994 a factory turbo option was provided for these engines (I'm not sure if it was available in the E-series or not). Several manufacturers (Banks, Hypermax, etc) provide aftermarket turbo kits for all of these normally aspirated engines which adds a significant amount of power and torque compared to stock.
In 1994.5, the 7.3 IDI Turbo was discontinued and the Powerstroke 7.3 was introduced. When you're looking at a rig from 1994 you need to look closely to distinguish which motor you are getting. The 7.3 Powerstroke engine was offered through 2003. There was a change or two along the way (1999-ish?) and there may be differences between the engine in the E- and F-Series. Hopefully someone with some PS knowledge can chime in or you can just google it.
The IDI engine is all mechanical and can literally run off of one wire. It does not make the power of the powerstroke or burn fuel as cleanly (iMHO), but they are known for being pretty bulletproof and simple to work on.
Hopefully that answers a little bit of your question!
2009 Express AWD, CCV Top & 50-ish home build. Daily driver/camper/kid hauler