Retrofitting a roof rack A friend is willing to sell me at a friendly price the Thule roof rack pictured below.



It's home will be a Subaru Outback that already has the crossbars (see the blue rectangles above)



Any thoughts on how to securely attach the red-highlighted racks above to the cross-bars below?
I took @Christopher Hunter's comment above an an answer, thank you:  I looked up Thule adapter and found a retail shop near my house.  I visited that shop today and was told that adapting was not possible:  the rack attaches to the roof bar in two places ... I could purchase a back "tie-down" that was wide enough to span the roof bar, but not the front.

I ended up buying two rockymounts brand tierods.  I have not yet installed them and can return them in case someone believes I chose poorly.