2.1K views · 840 reactions | Phil Dixon’s Commer “knocker”. This truck was designed with a unique opposed piston engine The engine was the first diesel developed by the London-based Rootes Group and the opposed-piston design was intended to allow the engine to fit under the seat of cab-over-engine trucks designed by company, dispensing with the bonnet or hood. On tour downunder with @chucksnowceo | Dean Croke | Facebook