By the way, this eBay auction shows your bike's predecessor, what I would extrapolate/speculate is a 1972 or 1973 C. Itoh Diamond Tourer:
https://www.ebay.com/itm/302289312070
Notice that the CrMo sticker is the same as that used on the 1974 and 1975 Diamonds.
If it were my size I would buy it.
T-Mar, what do you think about the Suntour parts and date on that eBay bike? Does my guess make sense?