This is something that gets discussed a lot on the forum.

Jeff is working on a page to cover the change from Cal 11 to the improved Cal 11i version : http://www.onthedash.com/docs/CompareCal11s.html

Dates are still to be sorted but problems seem to have cropped up pretty shortly after the Cal 11 was released. It would appear that the Cal 12 was quite possibly already being phased in during 1970 and is an improvement over the 11 and fixes its problems to a greater extent than the interim 11i - think quick fix versus permanent solution.

The Daytona doesn't appear in the brochures until 1977, so it's well into the lifetime of the Cal 12, which is the movement that they should all have. So could be a replacement movement in the one you've seen, or possibly just a replacement bridge - was the base plate rhodium-plated too?

Cal 11 here:

Cal 12 here: