here is a Schwinn / Huret GT 510 rear derailleur in good condition.  has shiny chrome with minor flaws up close

used on several models in the 1970s and early 1980s.  

Varsity, Suburban, Caliente, Continental, Sprint, Sportabout, Collegiate

 

be sure to check my other listings for more Schwinn parts, feel free to ask any questions.