TycoPro S1 Diecast Drop Arm prototype
(ed. note info provided by Pat Dennis 2015)

This is, to the best of my knowledge, the only surviving sample of this part.

A bit of history:
Shortly after the Tycopro was introduced, a material choice flaw was discovered. The acytel drop arm was not stiff enough to counteract the dynamics of turns, causing the car to deslot too easily. Looking at our train line, it was decided that we could combine an extremely stiff arm and the necessary weight by making the part from the Zamak diecasting material used in the locomotives.

It was a sound engineering solution to a problem with the S1, until I started thinking "outside of the box" - and convinced management that the stunt track sections were not a good ideal (I think I stressed the proposed safety regs and said that "racing the train to the crossing" would raise red flags), which opened the door for the TycoPro 2 with the drop pan.

Here's how it looks installed in a Series 1 chassis:
(click for larger)