Toad

= "Oliver stop!" = Little to nothing is know Where or What happen to Toad, But Scruffey saw Toad behind Oliver begging for It to stop.

The wagon's appearance
The GWR Toad is a class of railway brake van, designed by and built for the Great Western Railway. Used by the GWR from 1894, and post-1947 by the Western Region of British Railways.

Theory
He was in some yard before the nuclear meltdown, He was later picked up by Oliver with 2 Mail van believing he taking him to a safe place, Talking to Duck into following them (The beast tricked him) right before It happens...