American Top 40: The first two years or so of AT40 show clear evidence of a work in progress. Casey Kasem's delivery was much different during those first couple of years than what fans were accustomed to (c. 1973-late 1990s), and even his hosting style was noticeably different. There were relatively fewer stretch stories, with only brief facts about the artists to introduce the songs. Extras – usually oldies or album cuts from the No. 1 album of the week – filled out the show more often. Also, those early shows were in mono only; even FM stations of the time didn't have a stereo option. By late 1972, the show had just about taken the form fans would come to know and tune into for years to come.
Also, early episodes of AT40 had Casey Kasem attempting to predict what song was going to top the charts the proceeding week, after that week's number one single had finished airing. That was eventually phased out when it was no longer deemed a worthwhile part of the show. (By the way, you can still hear a lot of those earlier editions of AT40 on Sirius XM's '70s on 7 channel, since said channel picks from a range of episode years from 1970 - 1979.)
American Country Countdown: In addition to a different host altogether – Lubbock, Texas-based Don Bowman helmed the show – much like its sister program AT40, there were more extras and "sneak peek" songs played. In addition, during the earliest programs Bowman liberally made use of his humor in between songs, and many of his jokes today would be clearly considered politically incorrect today (e.g., on the third episode from October 1973, he quipped, "How do you get a horse to stop complaining about the cold in winter? Shoot him in the summertime!"); Bowman eventually scaled back on these jokes when complaint letters — calling the jokes mean-spirited — started coming again, and once Bob Kingsley came aboard as producer this could have had an impact, too. During the first year or so, outro bumpers (mixed in with the trademark "My Kind of Country, My Kind of Music" outros) sometimes used an alternate format with different lyrics and a top country artist of the day, including Bobby Bare and Tom T. Hall. Bob Kingsley took over in 1978, and hosted until 2006.
After Bob left, he was replaced by Kix Brooks of Brooks & Dunn. The earliest Kix programs from 2006 and 2007 often had him breaking away from the countdown to play songs he wrote for other artists, or Brooks & Dunn songs he sang lead on (including "You're Gonna Miss Me When I'm Gone," the only No. 1 B&D hit featuring Brooks on lead vocals). Over time, the "extra" songs came to be recent recurrents (big hits that fell off the charts within the past year or two), followed by a snippet on the artist in question. In addition, Kix's show was originally 40 positions like ACC was, but he cut it to 30 after program directors felt uncomfortable with the 31-40 songs being "unfamiliar". Apparently this was easier than, you know, adding said songs to their playlists earlier. (The show is still four hours long, thus leading to more filler songs and gabbing from Kix.)
Bob founded Bob Kingsley's Country Top 40 in 2006 after leaving ACC. His early CT40 shows had a couple lesser examples of this trope. Most notably, he originally used a Previously On segment identical to ACC's, consisting of the previous week's #1 hit, played either in its entirety or an edited-down version. This was quickly replaced by snippets of the previous week's Top 5 hits. It also took a couple years before he introduced "CT40 Flashback", a once-a-month segment just before the #5 song in which Bob presents trivia on a certain year in history, then plays snippets from the Top 5 songs on the corresponding month in that year.
The earlier episodes of Stus Show (from 2006 and some of 2007) had a more laid-back feel. Stu was more calm and collected, interviews were more straight-laced (but still had humorous moments here and there), phone calls from listeners was more regular, and Stu often had trivia contests for listeners (usually just before commercial breaks). The contests have since been relegated to the New Year's Eve or Christmas specials, as contests tended to detract from the interviews.
When True Capitalist began, Ghost was a fairly ordinary (if rather extreme) conservative talk show host. It wasn't until the more bizarre personalities like the Internet Buttstalker and the Ghetto Capitalist showed up that he fully became the Large Hambone that we know today.
The early instalments of The Goon Show had four people (the regular three plus Michael Bentine), and were written as multiple short sketches rather than the extended if incoherent stories featuring a Commedia Dell Arte Troupe of madmen that became the show's typical structure later in its life. It also took quite a while for Ned Seagoon, Bluebottle and Grytpype-Thynne to show up.