this might have been done before, and if it has let me know and i'll delete it.

songs from bands that were hits, but the usual lead singer did not sing.

drive - the cars - benjamin orr instead of ric ocasek

he can't love you - the michael stanley band - kevin raleigh instead of michael stanley

i can't tell you why - the eagles - timothy b. schmit instead of don henley or glenn frey

have fun...........................

"Stage Fright" The Band. Rick Danko is the lead singer instead of Levon Helm.

Happy--Rolling Stones (Keith instead of Mick)
These Dreams--Heart (Nancy Wilson instead of Ann; somewhat ironically, their first #1 single)

These Dreams, Nancy Wilson of Heart

Jinx

Does Your Mother Know--ABBA (Bjorn; maybe their only hit to feature one of the guys on lead vocals)

Beth--KISS (Peter Criss)

Something - The Beatles (George Harrison)
Harmony In My Head - The Buzzcocks (Steve Diggle)

Train In Vain---The Clash (Mick Jones instead of Joe Strummer)

Help Me Rhonda, with a rare lead vocal turn by Al Jardine instead of Mike Love or one of the Wilsons (and also one of their rare #1 songs)
Yellow Submarine with Ringo

did pete townshend ever sing lead vocals on one of the who's hits?

i think he shared lead vocals on 'baba o'reilly', but i don;t know if you call that a hit.

Numb--U2 (The Edge; not a big pop hit, but did reach #2 on the modern rock chart)

Death Of A Clown - The Kinks (Dave Davies)

I need a ruling from the judges on this one. The single was credited to Dave solo, but the exact same recording was included on the then-current Kinks album.

He sang lead on "Eminence Front"---not a big hit,but it still plays on the radio.

Squeeze - "Tempted" Lead vocal by Paul Carrack instead of Glenn Tilbrook

Correct me if I'm wrong, but I think Larry Lee of the Ozark Mountain Daredevils was not considered their main lead singer when he did "Jackie Blue"?

Good call. And this reminded me that "Cool For Cats," which was a hit single in the UK, featured Chris Difford on lead vocals.

Steely Dan - Dirty Work (David Palmer instead of Donald Fagen)

Don't know if this one really qualifies, because Benjamin Orr sang many of the band's hits. Ric Ocasek was the band's leader and songwriter, but I don't know if The Cars really had a "lead singer," as the lead vocal duties were divided between Ocasek and Orr.

My nomination:

"Dirty Work" by Steely Dan - vocals by David Palmer instead of Donald Fagen.

Yes, Orr sang tons of songs, at least half on every album including the very first hit The cars had "Just What I Needed." They had two lead singers.

"Dirty Work" was not a single and thus not a hit but certainly feels like a hit from tons of airplay.

"Oh What A Night (December 1963)" - Four Seasons

For the same reason as the Cars, this doesn't really qualify, as lead vocals were always divided among Richard, Levon and Rick.