1978 Gibson Quality / Prestige / Innovation catalog. Details of the Gibson SG Standard and L-6S Custom guitars
Like many other guitars produced in 1978, the SG Standard was being offered in a wider range of finishes than was previously the case. In addition to the three finishes offered in the 1975 solid bodies brochure (Cherry, Walnut and Sunburst), White was also offered - a finish more often associated with the SG Custom - but additionally Satin Walnut - a less highly polished version of Walnut, with a $20 cheaper price tag. These finishes had been produced in small number since 1976, but of the 2503 SG Standards shipped in 1978, only around 7% were White, and 3% Satin Walnut - compared to around 40% in the normal high-polished Walnut finish.
The L6-S was still available in the Natural, Ebony and Tobacco Sunburst finishes listed in price lists since 1975 - however it seems all finishes were equally priced. Between 1975 and 1977 Tobacco Sunburst commanded a $30 premium.
1978 US prices for these models were as follows: Gibson L-6S Custom: $589; SG Standard: $569 (Satin Walnut), $589 (all other finishes).