Ed Mines asked:
" In many photos (like the rebuilt USRA DS box cars and some PFE wood side reefers) it looks like these were wider than the grab irons on the right side."
The Safety Appliance requirements for the left side hand grabs read; "Dimensions--Minimum diameter, five-eighths (5/8) of an inch, wrought iron or steel, Minimum clear length, sixteen (16) inches, preferably twenty four (24) inches. Minimum clearance, two (2), preferably two and one half (2 1/2) inches".
The length requirement varied with each road or private owner's preference, and I would tend to believe the time frame in which cars were fitted with 30" grabs was more prevalent during the early (all wood) and composite car period and faded as all steel cars became the dominant newly built type.
As for modeling the longer grabs -- I would bend my own and add an NBW to simulate the attachment.