Voulk's Thomas School bus pack
Includes 4 buses: Freightliner FS-65, International S1800, International 3800 and a 4x4 monster bus.
pdn file included in the pack to make your own skin as well as a bunch of ready to use skin in the spec folder
More info: Voulk-s-school-bus-pack
No mods and no taking parts off from the buses. Skins are welcome.