In a race car, 9". Gear selection, hard core parts availability, aluminum case (weight), ability to keep the 4 link narrow and weld brackets and braces where ever they need to go, able to have multiple/spare centers ready, easy to work on.
Street/strip. Danas are ok. Cost less, weight not so much an issue, reliable and strong, and you're more likely to install it and forget it in that application.
I would put a Dana in a street car. A race car? 9". Some people like vanilla, some like chocolate. Pick your flavor.
If the results don't match the theory, change the theory.
