The length of Grandma Torque story can vary. Sometimes it's short and concise, while in other instances, it might be elaborated and longer. It all depends on who's sharing it and how they choose to present it.
If it's a simple adventure story, the jeep could be a means of transportation for the characters in the story, and the duck could be an unexpected and interesting addition. Maybe the duck represents the wild and free nature in contrast to the mechanical jeep.
If we consider a common understanding, 'shaft' can refer to different things like a long, narrow part or a passage. In some novels, if there is a description of a shaft as black, it might be for creating a certain atmosphere, perhaps a sense of mystery or gloom. However, again, without knowing the particular novel, it's just speculation.
Shaft visual novel could be a term for a visual novel that has some connection to Shaft. Shaft has created many visually striking anime series. In the context of a visual novel, it might imply a certain aesthetic quality similar to what Shaft brings to its anime works, like detailed character designs and elaborate backgrounds.
A jeep caricature usually exaggerates the shape and details of the jeep to create a funny or unique look. It might make the wheels huge or give the jeep a crazy color.