This morning I was able to escape from my [almost] 2 year old to grab some quick measurements. So i started my model with the factory rails... which, btw, are a PITA to measure. Especially since I couldnt find my protractor and I left my micrometer at work. So with some fancy level and scale work, plus some basic geometry, i think I got them pretty close (close enough to at least work on the design anyway).