Good call, though few of the tracks by either are A+ clavinet-dominant in the way, say, "Superstition", "You Haven't Done Nuthin'" or "Up On Cripple Creek" or even "Jeopardy" are.
Fagen is more of a Rhodes/Wurly kind of guy, but there is one track on "The Nightfly" with clavinet ... "Green Flower Street". That's about his batting average with clavinet and Dan too. Used sparingly with "Kid Charlemagne" the only one that jumps at me from the top of my head.
Edit: fork me. "Black Cow" has clavinet. Still, about an average of one per album.
Stevie? I was curious, so I looked it up.
"Hotter Than July", which came out in 1980, has three tracks with clavinet, including "I Ain't Gonna Stand For It" and "Master Blaster (Jammin')". I suppose I recall clavinet in those two, but they're nowhere near as prominent as in his early-to-mid-70s stuff. That was it. None of his other 80s albums had it, which stands to reason, given that he always wanted to be at the cutting edge of keyboards/synths.