At 13:18 11/21/2016, Dennis Haynes wrote:
>preset speed. I forgot which is which but one is 750 rpm and the
>other is a worthless 650 rpm. I have yet to see one actually go bad
>except for extreme corrosion on the terminals.

251 906 083 is for California, and for Federal 83.5.  I think it's
the green one, and it's set 100 rpm faster than the other.  I *think*
it's 850/750, but there's some text in Bentley that suggests it might
be 950/850.

321 906 083 is for Federal '84-5.

I used both on my '84 Westy (Cal-spec, originally bought in Michigan
and delivered in Germany) and they really did make the idle sturdier.

Yrs,
d