I have them on my Dodge and my Ford.
On the cap of my dodge, I have Thule tracks bolted through with Yakima towers and cross bars.
On my Ford cap I have the Yakima "Landing Pads" which are bolted through with Yakima cross bars
On both of them I carry two long sea kayaks sometimes on J cradles and other times on regular saddles and at the same time I carry a 17 foot canoe between them.
I also have a set of cross bars on the cab roof using Yakima thingies that are like a big toggle bar which doesn't come through the headliner.
Jack L
Jack & Nanci