Zinger, with that HDI unit you will not be able to use the US2, so no adapter necessary. Next take your terrova and put the ducer cable in the slot on the shaft of motor. You need to check if it will fit all the way into the slot so motor can slide up and down through bracket if cable was installed into that slot. Humminbird cables will fit so you run cable up through head of unit and out to finder. Most of you Lowrance units cable is to fat for slot. I just haven't had my hands on your unit so have no idea on cable size. If that won't work next best thing is this.
da 'ducer apparatus - Podunk (po dungk) A small isolated town, region, or place that is regarded as unimportant. . . .
This is what CanePole installed on his Pondtoon for Lowrance transducers.
Proud Member of Team Geezer
Charlie Weaver USN/ENC 1965-1979