I remember seeing Shatner and Nimoy on a game show (I think it was the Match Game) shortly after the Original Series was canceled. Shatner behaved like a total goofball. It was almost as if he was trying to distance himself from the Kirk character. Nimoy was basically the same as he is today. And Shatner behaved more like you see him nowadays as Denny Crane with a lot of silliness and forced humor. I think The Shat was afraid of being typecast while Nimoy was happy to be cast at all. Funny since Nimoy had an easier time of it immediately after TOS.