Not specifically on Sesame Street....but Big Bird, Grover, and Oscar make appearances on The Electric Company ---- all on this set.
Big Bird is in a Fargo North Sketch trying to decode a message about him trying to find home.
Grover is in Vi's Dinner upset because he can't remember where he lives (duh???)
Oscar does a duet with J Arthur Crank.
--RE Sketches that are also on SS... there was a cartoon that had to do with a machine that spitted out stuff that begins with M such as Marshmallows, Meatballs, Mud, and Melons....then mistake (the man gets sucked up by the machine and then spitted out). This cartoon reminds me of the SS Cartoons....whether they actually appeared on SS I can't answer that.