Max and Monty are two Devious and Troublesome Dump truck Twins. They are numbered 15 and 16.
Max and Monty were reckless, rude, devious and troublesome. Despite this, They were being good hearted when they are sternly scolded by Miss Jenny.
- Season 7: Stanley, Whiff, and The Troublesome Dumptrucks
- Season 8: A Challenge for the Controller, Tick-Tock-Jock (cameo) and The Almighty Alfie
- Season 11: Duncan in the Dumps (do not speak)
- Season 12: Greetings, Montague! (not named; do not speak), Scottish Blues (mentioned), Percy Gets a Promotion, Bulgy Takes the High Road (cameo) and The Mystery Train (cameo)
- Season 13: The Duke of Hazard (do not speak), Oliver's Fossil Fright and Ivo Hugh's Day at the Zoo (cameo)
- Season 14: James in a Jam (Max only, cameo)
- Season 15: Jock Beats the Clock (cameo) and The Island Of Misfit Engines (cameo)
- Season 16: Sweet Sixteen (cameo), Luke Dukes It Out (cameo) and Knock it Off, Stanley (cameo)
- Season 17: Hard to Handel (cameo), Oliver Confusion (cameo), Thomas' Crown Affair (cameo), and Para-Norman Activity (cameo)
- Saving Pirate Ryan (Max only; Monty cameo)