Here’s a shot featuring the three generations of Grand Seiko 57’s. On top, the 43999. This watch is the SD dial version, and the serial number dates it to August 1963, which is believed to be the first month of production for this model. As mentioned previously, personally I like to consider this model in its own 43 series rather than bundling it in with the others!
Underneath on the left, a 5722-9990 from 1965, and on the right, a 5722-9991 from 1967.
This is by no means representative of all variants of the vintage 57GS series, but it does cover the full range of calibres that were used. The 430 in the 43999, the 5722A in the 5722-9990, and finally the 5722B in the 5722-9991.