Day after day, for a full year, Howard Stern has laced his morning talk show with promotions for his impending move to satellite radio. Why did dozens of radio stations let him use a year of valuable morning drive time to push their competition?

They didn't have anything better to put on the air.

Now, with just a few weeks left before the $500 million man takes his act to Sirius pay radio Jan. 3, the stations that depend on Stern's show for much of their revenue have announced their succession plans, and the underwhelming results explain the long delay in filling Stern's slot.

After approaching a slew of big names about taking on the early morning radio show, Infinity Broadcasting settled on a bunch of semi-celebrities in various cities where it owns FM talk stations. So instead of Whoopi Goldberg, Jon Stewart or Geraldo Rivera, listeners who used to wake up to Stern will find TV comedian Adam Carolla in Los Angeles, ex-Van Halen lead singer David Lee Roth in New York, and the Junkies -- four pals from Prince George's County who yak and crack wise about sex, sports and TV -- on Washington's WJFK (106.7 FM) and Baltimore's WHFS (105.7). Magician-comedian Penn Jillette will launch a one-hour talk show to air later in the day on nine stations, including WJFK.

In any business, only the most courageous yearn to fill the shoes of a huge success. Stern was one of the handful of top performers in radio, which faces difficult times because of declining audiences, competition from other media and the advent of satellite services (which need not conform to federal regulations on obscenity).

Although Stern's show aired in far fewer markets than the likes of Rush Limbaugh or Laura Schlessinger, he delivered a young male audience that is hard to come by in an era in which iPods, video games and other razzle-dazzle technologies provide alluring distraction.

Stern has marveled on the air that Infinity let this year go by without getting successors in place or putting him on ice. "That shows you how important -- and how irreplaceable -- the revenue from the Stern show is to those Infinity stations," says an executive at a rival radio company who would not be named because his bosses have forbidden public comment on the Stern story. "They wanted to grab every last dollar they could from having him around."

Stern's show aired in 38 markets, including 27 Infinity stations, such as WJFK here. Now, Infinity will seek to let half a dozen flowers bloom. By taking a chance on Roth, whose show will run on five stations from Boston to Dallas, and Carolla, who will air on six stations out West, Infinity can satisfy stockholders' desire for name talent. In other markets, the company will try to develop new stars. Two Infinity executives who said they were not permitted to speak publicly about the succession said few in the company believe Roth and Carolla are long-term solutions. "Neither of those guys is going to last long once they see what it's like to get up at 3 a.m. every single day," one manager said.

"Stern's departure is the worst natural disaster to hit a media company in the decade since consolidation," the mid-1990s gold rush when a handful of companies bought more than a thousand stations, says a talk radio executive who is involved in the Stern succession decision process. "Even though he was only on four hours a day, many of the sponsors on his show were required to buy time through the rest of the day as a price for getting spots on the Stern show."

Infinity executives argue that it may be easier to sell ad time to some businesses that didn't want to be associated with Stern's daily parade of strippers and porn stars. But competitors say that's just spin. They point instead to Infinity Chairman Joel Hollander's decision to let Stern stay on the air all year as proof that the company knows it will not be able to match Stern's ad billings.

While Infinity tries to position its stations as an alternative to pay satellite radio, rebranding talk stations such as WJFK as "FreeFM," other stations are also going after Stern's audience. In Washington, WMET (1160 AM), which draws a barely measurable audience to a lineup of conservative talk shows, has brought on Doug Tracht, the Greaseman, who succeeded Stern at DC101 in 1982 when they were the fresh bad boys of Washington radio.

And Stern's erstwhile competitors are trolling for new markets. Erich "Mancow" Muller, who came to fame in San Francisco when he sat for a haircut in the middle of the Bay Bridge, snarling traffic and earning his station $1 million in fines and priceless publicity, has been beating Stern in the ratings in Chicago for years and is now adding stations. Like most raunch radio jocks, Mancow, who has won national notice through his regular appearances on Fox News Channel's morning show, has toned down his act since last year's Janet Jackson nipple incident brought the fear of the FCC upon broadcasting companies.

Sales executives pushing alternative acts cite research indicating that Stern's audience will be casting about for new diversions during morning drive time. Sirius, meanwhile, points to research that says Stern listeners are strongly considering buying satellite radios to keep listening to their favorite show. From July through September, Sirius's share of retail sales of satellite radios has jumped from 40 percent to 56 percent against its competitor, Washington-based XM Satellite Radio, according to sales data from NPD Group. XM holds onto a strong lead in the sales of factory-installed satellite car radios.

Stern is gleeful on the air about the uncertainty at Infinity. "While these clowns are trying to fill time," he said the other day, "I've got plans for two spectacular channels for you."

Howard Stern's move to satellite radio will leave quite a void.Former Van Halen lead singer David Lee Roth will be heard yakking for Infinity on five stations from Boston to Dallas.TV comedian Adam Carolla, known for his humorous work on "The Man Show," takes over on six Infinity stations out West, including Los Angeles.