Thats a good find Rob how did you come to find that.. lol

They come on other engines too, the best way to describe it would be to look for the 3 external bolts that hold the starter motor together. Most of the time they are galvanised gold ish colour, as there not that old most of them are in still good working condition.

As stated they are very small compared to the std items and also have a higher cranking speed.