Q: Cruising steadily, loss of acceleration, and engine cutting out

I was driving down the highway, cruising at about 50 MPH, when I experienced a loss of acceleration. Shortly after, complete loss of power and the engine cut off. I was able to, safely, roll to the side of the road where I sat and tried to diagnose the problem for a few hours but eventually had to call a tow truck. My vehicle is a 1990 Chevy Blue Bird Mini Bird, with a 6.2 diesel engine and a Turbo 400 transmission. It is based on the P30 step-van chassis. I was able to narrow it down to a fuel problem.. every time I try to crank the engine again, it sounds like it's going to start but it just won't. I don't believe there was fuel coming out of the fuel injectors (if there was, very little). One of the first things I checked was the tank (and I had plenty of fuel). My mechanic is telling me the fuel distributor (and the o-ring in it) needs to be rebuilt, probably, however I don't see anything online about a fuel distributor with my vehicle. Any thoughts or, hopefully, good news?

My car has 217000 miles.
My car has an automatic transmission.