Dennis is a lazy gray diesel.
- Dennis with roof tile trucks (Plarail, Motor Road and Rail, TrackMaster [HiT Toy Company])
- Dennis with two half straight track pieces (Motor Road and Rail [US])
- Dennis with half straight track piece (TrackMaster [HiT Toy Company])
- Dennis with blue truck (TrackMaster [Fisher-Price])
- Dennis (TrackMaster [Fisher-Price])
- Dennis' traction rods are unique to his model.
- Dennis' wheels are different to other engines' wheels. Instead of straight lines, or "spokes", in their place are indented oval shapes. The same thing applies with Neville
- His number is placed onto his sides, when it should had been placed onto his cab.