A bit more info:
The reefer and coal car underframes appear to be substantially the same. Interestingly, my button herald reefer has screws attaching the draft gear boxes, whereas my block-lettered reefer has the same plastic pins as my coal cars (both button herald and block-lettered).
The more substantial difference is that the reefers have the front facings of draft gear boxes cast into the shell. This is going to foul the front lip of the Accumate boxes, pushing them lower and perhaps in turn creating more fouling issues with the trucks.
It’s possible removing the top front lip of the Accumate boxes would alleviate this.
But I’m not entirely convinced that this difference can account for the entire discrepancy between my coal car curve-tolerance estimations and Dale’s reefer curve-tolerance experiences.