From S. P. Fjestad (Blue Book):
During the period from 1975-1977 Gibson used a transfer that had eight digit numbers, the first two
indicate the year, 99=1975, 00=1976 and 06=1977, the following six digits are in the 100000 to 200000
range. MADE IN USA were also included on the transfer and some models had LIMITED EDITION also
applied. A few bolt on neck instruments had a date ink stamped on the heel area.
I wasn't aware that the RD Standard was out as early as 1977, but since yours has 1977 pots, this very well could be missing a decal.