I've recently added an 8x56 T*P* to my group with serial number 403228. So this would be 1990 or later production? I had a T*, no P, during the 1990's, excellent for astronomy and light enough to carry around during the day too. I found a very clean one on fleabay and decided to try it again. I believe it's only 35 ounces which is amazing for a 56mm binocular. It showed up out of alignment and with stiffened focuser so it's being serviced by Zeiss in Germany now, I'm glad they were able to work on them.
There are some differences b/w the 7x42 and 8x56....AFOV is smaller on the 8x, and color correction isn't as good. I can't wait to get these back! Very difficult to find a clean one, as they seemed to be used mostly for hunting.
The current SF's seem like the heirs to the Dialyt legacy. The hold and balance on them is similar, and the longer focal length design, and the light weight. The 8x56 have the same "air" feeling to them, just like the 8x42SF. They're lighter than the typical 50mm porros from those days.