If you are talking about the brass elbow that recieves the brass body, I see that the one I took off my '85
Sovereign is cracked as well. This is undoubtedly the fate off all these plastic pieces from that era, as is the reason so many of us I replaced the grey plastic plumbing.
I went with the "hole in the trailer" method, and really think it is an improvement. If you must have one, however, there is likely one still on an '86 Sovereing at Colaws RV Salvage -
http://www.colawrvsalvage.com/
Mark