where to mount a new ballast resistor?

[Spitfire 1500 <s1500@comcast.net>]

In an attempt to get the tach to read right, I bought a ballast resistor. 
Where's a good place to mount this? I have the area where the old (unused) 
drive 
resistor used to be available. I saw a picture where it's mounted on top of 
someone's PWDA(through a longer sized bolt), but that seems odd to me.


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