Intermountain keeps numbering these for #68000-683999, which were built by ACF, and were welded panel cars, like in the photos above. The correct numbers for the PCF built cars, should be #68400-68649. The intermountain cars are actually accurate for this number series, with the exception, that they should have a diagonal panel roof. A lot of these were renumbered into the WFBX series for use as potato reefers, in later years. Check for photos of the WFBX cars and you will find some that match the IM reefers.
Albert Spor