I'm not a Schwinn expert by any stretch, but I understand that Nervex Pro lugs were introduced around 1959 or 1960. I think Schwinn stopped using the Nervex BB shell sometime around 1963-65. Many bikes from many nations seem to have a simular cutoff period for the use of Nervex BB shells, but I don't know why. The deffinite exception would be Peugeot. I remember my 1971 PX-10 still had a Nervex BB shell. I think the French threaded shells persisted much longer than the English or Italian thread versions. My '62 Masi Special has a Nervex shell but I've not seen a Masi newer than about 1963 with one on it.
I haven't checked out your frame, but I would say it's the older date as opposed to a bike from the 70's.
La Mesa, CA
> I have just got a paramount with seriel # H75 and thought it was a 75model
> year.Using waterfords dating system it shows to be a 1961 bike? The question is
> did they use nervex pro lugs and bottom brackets and campy dropouts back then
> and what year did they start using these parts when building frames.
> I also just received a dura ace dropout and der. hanger alignment tool and it
> looks to be like a well made tool, did shimano make a complete tool set like
> Jimmy Katynski
> Madison Heights Mi