1971 GS Disc brakes?

I am looking at a 1971 GS 350 that is numbers matching car and it has drum brakes! I thought all GS's had discs in front. Were disc brakes an option or should I check the numbers more closely?.

 

The order form in section C is as follows

C1 - Power Disc Brakes
C6 - Power Steering
C7 - Power Brakes(I assume drums)
CC - C6 + C7
CE - C1 + C6

 

71-2 BBB GS models had disc brakes standard.....SBB had drums standard.

 

0n your car they were an option.