"Old Rueben" as sung by Wade Mainer, has the line "Number 9 had a wreck".
Both "Old Rueben" (Wade Mainer) and "If I Die a Railroad Man" (Tenneva Ramblers) have a verse like this:
"If I die a railroad man
You can bury me beneath the sand
Where I can hear old number 9
As she goes by"

Also, I recall "Engine engine number 9" as "Coming down Chicago line". I believe my aunt remembers it the same way. We both would have heard it in Southern California, her in the 1960s and me in the 1990s/2000s.