I have one of the 1980s NYC Transfer Cabooses that is missing 2-3 handrails.
It looks like LIONEL might still make this model as Bethlehem Steel, and another version for the SODOR Work Train (Thomas related)
I could find the Bethlehem Steel page on the LIONEL website - but didn't see that part referenced - at least not obviously.
Couldn't find the SODOR/Thomas version at all - but didn't really have a SKU.
Hoping the newer version parts are available and will retro-fit the older versions.