I picked a couple cars I converted.. Where the dependencies come from... The CSX is similar to the prototype photo below, but only has MAX GROSS WEIGHT that is 260,100 lbs... So not quite the 263,000 as noted above, but YET has is not the 220,000 that many other 86' boxcars seem to have...
The CSX more closely follows the prototype photo above with the increase weight car data matching what's stamped on the ends for 36" wheels
However, check out NS, could be that shopped scenario.. clearly the weight data falls in-line to the 70-ton trucks discussion, but yet is stamped 36" wheels. Maybe captive service on the NS and they are carrying heavier loads thus the needs for 100-ton trucks?