I think most that were ordered w the 7.3 were intended to work. And if they worked hard they are long gone. Ive seen a few conversion and club wagon 7.3 diesels on Facebook marketplace or craigslist. I don't consider 6.0 diesel vans for me.
I bought both of my e350 diesels on gov deals. I did a quick search and 30ish sold over the last 60days. Most were e450 ambulances or box trucks. With a few e350 cargo vans and other work vans.

 

Plenty of diesel Econolines even in Finland.
Not so rare,but really good ones are hard to find, because these era Fords were made for working.
I mean them were made like tractors,not like Chevys.