I just recently purchased a Ford 3000 diesel and had to figure out all the numbers. From what I learned, if your serial number starts with a B is was built in Basildon, England. The 8C05B should be the date code, which means it was built on March 5, 1968 by the day shift. I am not sure about the 21023B number but I think it should interpet as a Ford 2000(2), Agricultural All Purpose (10), Gas (2), Live 540 PTO (3) but I am not sure about the B in the number unless that indicates the 6 speed transmission.
Hope this helps,