The 412 diner of Tonawanda NY has reopened.
Story about the reopening

Just wanted to clear some things up about the diner.
From the article:
“a pre-1900 train car”
“peculiar wooden train-car-turned-diner”
“the old car was a trailer used to feed workers on the Erie Canal”
“details scarce about the car’s history”
” ‘modern’ tile work that was still likely installed before some readers were born”

The diner looks to me like an old O’Mahony or a Tierney (their products were similar) with renovations, most notably to the windows and facade. Definitely not a train car, and not from 1910.
In old pictures, it had roughly the original shaped windows (now they’re bigger) and a sliding door facing the street. The tilework, noted as one of the changes since new, appears to be one of the most original aspects of the place.

The 412 has the same vent hood as Letterman’s diner, which has been confirmed as an O’Mahony

Letterman’s before it was encased

Kaspar’s diner- the “Victory” model- advertised in O’Mahony’s c.1943 Catalog This model was an update on what they were producing through the 1920s.

A 1926 Tierney

Dan’s Diner of Spencertown, NY. Photos from their facebook Page. Dan’s is a 1925 O’Mahony.