I have a set of Thule "short roof adapters" for the old rectangular cross bars/feet mounting system.  

If you have a coupe or small car, these help space the feet on the roof further apart so the system is  more stable on the car.  

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they look like this, I have all the mounting bits.  

Make an offer?  Trade me something?  

Also have some Thule feet and clips, but I'll have to dig those out and see what they fit.
Pic is not my stuff, but looks like that.