Uhoh, you're giving me credit where it's not deserved!
You're in good hands with QB, though.
If I could add a bit about boxcars: The 40' boxcar you referenced earlier went the way of the dodo ages ago. Up until, say, 15 years ago, the standard boxcar was the 70-ton, plate C 50' and 60' car. Today, the boxcar of choice is the 110-ton, plate F 50' and 60' car. (Those cars can be ID'd by the white ends below the roof profile to signify the plate F height.) Going back to the discussion on weight and cube advantages, here's why the plate C car is passe: Today's standard 53' trailer (or domestic intermodal container) has a loading capacity of ~24 tons/4000 cu ft. The low cap'y, plate C car has a ~1.5:1 cube advantage and a 3.25:1 weight advantage. In contrast, the high cap'y, plate F car has between a 1.75:1 (50') to 2.1:1 (60') cube advantage and a 4.25:1 weight advantage (if the railroad can handle 286K). Consider this: about 5-7 years ago, about 225,000 boxcars plied the rails. Today, the count is down to about 125,000. Now, part of the decline can be attributed to the improved efficiency of the high cap'y cars, and boxcars ain't going away any time soon. But I wouldn't expect a market renaissance.
By the way, if the likes of Senators Collins and Snowe get their way in pushing through more liberal over-the-road weight laws (from 80,000 to 97,000lbs with the addition of a third axle), those weight ratio advantages will narrow, further compromising the viability of the plate C cars (and plate F cars, for that matter).
To your points on pulpwood and chips... I don't believe pulpwood's primary issue is weight but proximity to consumption point. However, woodchips are (a) not dense, and (b) low value. Google "NS wood chip car" cand you'll see how huge these cars have become to be economically viable.