Actually it is NOT a Shanghai 760a, but the base model Shanghai 760 produced from 1964 through 1967. In 1968 through 1991 it appeared with cosmetic changes and subsequent suffix additions to the model designation ........ 760A, 760B etc.
The posted picture with the horizontal ribs between the simple rectangular taillights indicates it is an early production run 1964-67.
Earlier versions of the same based vehicle from 1958 to 1963 were named the Fenghuang or (Phoenix in English).
All 760/Fenghuang vehicles used a cabin architecture heavily borrowed from the Mercedes Benz 220 from the 1950s as well as thinly disguised mechanicals from the same era M-B.