[jeffschevelle]

Except for some of the smog cars, all 65-67E are straight, unthreaded press-in pipes with no lip. But they are an odd O.D. size not sold by standard pipe vendors.

As to Paragon, if you Google Paragon Corvette you get Paragon Performance C8 (apparently a different company), and you get Corvette Central which indicates that it is now selling parts from Paragon (or formerly from Paragon ??). There is no indication of Paragon being in retail sales itself anymore.

And Corvette Central only lists the second design pipe with the lip on it. Whoever repopped it just copied the later style pipe (probably copied an NOS replacement pipe since they were still available for decades). GM discontinued the early style pipe as a service replacement part in 1968, so not much chance of ever finding an NOS one still floating around ...