It's funny. I live in Connecticut now, and on a somewhat regular basis, I imagine myself back trackside at a variety of places in Michigan and the Midwest. But rarely do I wish to be someplace like Fostoria, or on the Water Level Route. Often, I wish for shortline or out-of-the-way action, or some diamond around the state. It wasn't all that long ago that I thought back to a day a few years ago when I saw four of the six trains which regularly cross Diann diamond in any single day. Not exactly thrilling action most of the time! But as was posted earlier, during these long summer days, one can often see the morning southbound Annie, a CN train, and then the I&O if it happens to be one of the days they come up to Flat Rock. The day I recall I saw the southbound Annie, then the northbound CN (M384?), then the northbound I&O, and then I moved up toward Flat Rock a ways to see the I&O return an hour or two later. The anticipation and beautiful farm scenery down that way makes it all worth it

Yes, traffic is down somewhat from what people will remember a few years ago, but don't forget I&O lost all of the regular autorack traffic into and out of Flat Rock Yard - which was all bridge traffic and didn't kick in much to the bottom line. Now what you see is actually generating real income for the I&O. Great to hear about the jet fuel business, hopefully it's lucrative enough to keep going, adding a few more cars to the mixed freight consists.
Robert, your photo of 4072 leading long hood forward through Carleton is fantastic! Somewhere I have a photo from the exact same spot about 10 years ago of the southbound I&O with a NYS&W "Susie-Q" SD70M leading. Not too many tunnel motors can be found in Michigan these days!
A few years ago, I&O 4083 was the regular power on this run. These scenes were recorded in June 2010:
First northbound 401 passing a centennial farm just north of Diann:

And the return trip later in the day, southbound 400 near Raisinville:

The CN stretch of the Flat Rock Sub north of Diann is in good shape and these guys really haul. South of the diamond the speed limit is lower.