In the 1971 options list it actually doesnt list a spot light!
Below fog lamp it lists, Long range driving lamp!
Lucas lamps are FL8 and LR8,"Fog Lamp and Long Range",so in conclusion I think the actual change would of been for the 1971 launch of the 3500S,being the 1st print of the updated options list for the S2 to include the 3500S!
Also noted that door mirrors were not offered on S1's! only S2's.