In researching some older cars built in the 1900s to about 1916 it seems
that these were more likely to have wider handholds, often around 20-21
inches. That’s not a hard and fast rule, but simply an observation that the
wider type were more often seen on older cars - you still need photos or
drawings to refer to.

Interestingly it seems that some more frugal railroads *may* have reused
fittings from scrapped cars when adding the second hand hold on the left
hand side after these were required. I have a couple of photos where the
original lower hand hold is about 18 inches wide while the upper handhold is
about 21 or 24 inches

Aidrian