This is from the New York web page but many states have similar legislation which follows the federal requirements. 

Pursuant to 6 NYCRR Part 218-7.2(c)(2), and effective June 1, 2013, it will be unlawful for any person to sell, offer for sale, advertise, or install any used, recycled, or salvaged catalytic converter on any vehicle in New York State. This prohibition will apply to all vehicle types and model years. A used catalytic converter is not a new aftermarket catalytic converter, or a replacement part as defined below. This prohibition does not apply to the sale of used catalytic converters for recycling purposes. Pursuant to 6 NYCRR Part 218-7.2(c)(2), and effective June 1, 2013, it will be unlawful for any person to sell, offer for sale, advertise, or install any used, recycled, or salvaged catalytic converter on any vehicle in New York State. This prohibition will apply to all vehicle types and model years. A used catalytic converter is not a new aftermarket catalytic converter, or a replacement part as defined below. This prohibition does not apply to the sale of used catalytic converters for recycling purposes.

Dennis

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of Fuzzy :philippe
Sent: Sunday, August 31, 2014 11:40 PM
To: vanagon@GERRY.VANAGON.COM
Subject: WTB: Used working catalytic converter

Does anyone have one lying around?

It's for my '87 Van GL 2.1L

Thanks!

Philippe