Easy to make one - RadShack is still selling the required chokes. Digikey, Mouser or a similar company may have them as well.
You'll need two 100uH RF chokes (273-102)
http://www.radioshack.com/product/index.jsp?productId=2103978
and a connector set (P/N 02650) from The Electrical Connection:
http://www.electricalconnection.com/electrical-components/hitachi.htm
The chokes are connected in series - male pin to female pin - observing the same polarity through the circuit. In other words...you don't want to "cross the streams".
<--------()()()()()()()--------<
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Is a fairly good representation of how the assembly looks; the left side is the male 2p Hitachi connector (which attaches to the fan connector) while the right side is the female 2p Hitachi connector (which attaches to the "supply" side of the circuit.
Cover each choke with heat shrink tubing before assembly, so the windings won't rub and eventually short positive/negative together. Then cover everything with a larger piece of heat shrink tubing; fill the void with some clear RTV silicone and shrink the outer tubing.
I would use an insulated 22ga flexible wire lead of around 3" length off each choke, as per Honda's design. These can be tie-wrapped together to add mechanical strength to the assembly.
