Jeff,

The color and metal ferrule makes it earlier than 1973 as best I know. I don't know when the ferrulite ferrule was introduced, and Jimmy Green passed away last Saturday, so we can't ask him. I think all the metal ferrule series are from the 1960s. I first saw ferrulite ferrules in 1971 or 1972.

Fenwick did make an early 70s ferrulite model labeled FF80, FF84, FF85 before they added line weight designations along with length to the rod model number.

If the rods were built up from blanks, they might still read "Grizzly" or "Grizzly-Fenwick" on them, which is how the yellow blanks were labeled. The factory built rods were labeled "Fenwick." I'm not sure what thread color says about age, especially given that thread color fades, and lots of older rods have be re-wrapped as new guides were needed.

Go ahead and email a photo if you like, but I really am not an expert, just recalling from memory, as that was the time period I became obsessed with fly fishing.

Sincerely,

Salmo g.