Not all Runtz-style solid-state diode-based reducers have 3 terminals. The one from Classic Parts does not and the one for $3.00 does not. All Runtz-resistors are one-way - if installed backwards they either do not work or they fry?
The Classic Parts reducer (and many others) are cleverly made so that they can only be installed in the correct orientation.
$3.00 - autowire.com $6.00 - Classic Parts (I have one that has been in use for 17 years.
$17.99 - speedway motors 
