My guess is that 3M E 6 will be late 70s or early 80s emulsion, I doubt that Ferrania updated prior to pulling the plug on production sometime in the late 80s or early 90s, the last C 41 Solar 100 and 200 I used was a newer film developed in the 90s, as I recall the grain was good with a shift towards yellow. I have a few rolls of Solar 100 in the freezer. I need to check out smy slides from the
70s, I shot a fair amount with the old 3 M E 6 sold at K Mart, I dont recall off the top of my head if it was an ASA 64, 100 or 200. The last I looked they have held up over the years, unlike GAF which are all fading. .