I think these Classic gold plated nibs came out quite late on in Targa production, maybe in the early to mid 1990's. I know that was the case in the UK, because our Sheaffer reps told us to fit them to the Targa pens if our customers wanted to pay a little less. I don't beleive they came fitted as standard to any models, however I know they were also used on corporate pens to keep the cost down.
Cheers
Gary