I purchased this Accutron new in 1969 and purchased the gold band in 1971 from Corrigans in Dallas, Texas. The tuning fork hums perfectly and it keeps good time. The gold content is 54 grams and was valued at $985 in August, 2013. Contact me for additional information and photos. jcw77@me.com
Ah, the new photos clear it all up. M8 designates a 1968 date code not 1958, could you please update the root record to correct the year? It appears the movement is a 2182. The 218 series was the second Accutron version. The first version, 214 is recognizable by the absence of a winding crown as it had a back set feature. As Mark states above, 1965 was the first year for the 218 version.
This watch is the Day & Date "C" model. Ad is dated 1969. It's my opinion that Bulova was hesitant to advertise solid gold watches, I was a bit surprised to find this ad. I wonder if they were adverse to publishing prices on solid gold pieces?