The reason we chose the 1927 version is that ladders were used instead of just hand grabs. I¡¯m guessing someone figured out that the ice reefers were loosing cold by the through bolted fasteners for handgrabs. for 7 handgrabs, 14 steel threaded rods were needed, for 7 rungs of a ladder only 6. So multiply by 4, that might have been a big difference. If you want Further back, exchange the fishbelly centersill for trussrods.
Don?
Don Thompson