Today I finally saw the original 1977 pilot episode with Mark Hamill as David. The last time I saw it was in 1977 when I was only 4 so I don't really remember it. It is also amazing how much changed after only one episode. There are different actors and actress portraying David, Tommy and Nancy. It looks like CTS didn't edit the credits or the instrumental theme song from the pilot episode either.

Yeah, isn't that a strange episode? Even though it still has the laugh track, it's quite a bit more serious than the episodes that followed it.

Mark Hamill played David in the pilot, and was quite good -- his David was more rebellious and serious than Grant Goodeve, who usually came off as more immature and lightweight. In the pilot, David and Tom are portrayed as not getting along at all, which was softened later on. After filming the pilot, Mark tried to get out of his contract because he realized that he had a shot at a film career with the upcoming "Star Wars". But ABC liked the idea of having a movie actor in the series and wouldn't release him. Then, a few weeks before the regular series began filming, Mark was in a serious car accident and had to have plastic surgery. He couldn't appear on camera at that point, so he had to be replaced.

Kimberly Beck played Nancy in the pilot, and I've read that she was replaced because ABC felt that she looked too old. Which is really strange, since she is actually four years younger than her replacement, Dianne Kay. Chris English played Tommy in the pilot, and he seems like he was several years younger than Willie Aames, who replaced him. My guess is that the producers felt that a teenaged Tommy would provide more story lines than a 12-year-old one.