Is it indeed a home made tool?
The teeth are pretty well cut, and if was home made, the guy was pretty handy. It's a milled finish, but it hasn't had the same black coloured tempered finishing treatment of some of my other factory tools. On reflection, I guess with this sort of tool you want to ensure that it is sacrificial to the gear when engaged. Following Eldert's identification (thanks again, Eldert) I went scouring through some owners manuals for pictures. I found this pic in the 450 Owners manual, so maybe it is a factory tool, or a least a good reproduction of one. (apologies for the quality - it's probably a scan of a copy of a copy of a...)


Kev