RMSX is Harsco Track technologies. Pandrol Jackson was a company that ran rail grinding trains. Formerly Speno.
RMSX 0401 is one of the locomotives from their train RMS-4. Ex CR GP38 rebuilt by Speno with an extended cab and a cowl-type body.
Somewhere, there should be a train with 2 coaches, a couple of tank cars, 3 grinding cars and 2 power cars, and a mate to 0401.
(Info from Canadian Trackside Guide 2004)