Snowplows and snowblowers as standalone machines or towed units are classified under 843020 within heading 8430. A snowplow blade designed solely as an attachment for a specific vehicle may be classified differently depending on whether it constitutes a part of the vehicle or a separate implement; the principal-function and parts-versus-machine distinction governs that determination.

Horizontal directional drilling rigs that are self-propelled fall under heading 8429 (specifically the shovel and excavator subheadings or 842959). Non-self-propelled HDD equipment and boring or sinking machinery are classified under 843041 (self-propelled) or 843049 (non-self-propelled) within heading 8430, depending on whether the rig moves under its own power. The self-propulsion test is the primary dividing line.