Title: South 65
Content: Bruce Bouton – steel guitar ; Mike Brignardello – bass guitar ; Dennis Burnside – piano ; Mike Chapman – bass guitar ; Tabitha Fair – background vocals ; Owen Hale – drums ; Chris Leuzinger – electric guitar ; Greg Morrow – drums ; Steve Nathan – synthesizer ; Danny Parks – acoustic guitar ; Barry Walsh – piano ; Biff Watson – acoustic guitar ; John Willis – acoustic guitar ; Curtis Young – background vocals As listed on Allmusic.
Title: 25 or 6 to 4
Content: Peter Cetera – lead vocals, bass ; Terry Kath – guitar, backing vocals ; Robert Lamm – piano, backing vocals ; Danny Seraphine – drums ; Jimmy Pankow – trombone ; Lee Loughnane – trumpet ; Walt Parazaider – tenor saxophone 
Title: South 65
Content: David Angel – strings ; Eddie Bayers – drums ; Larry Beaird – acoustic guitar ; David Briggs – piano ; Arbry Burcon – banjo ; David Davidson – strings ; Dan Dugmore – steel guitar ; Larry Franklin – fiddle ; Paul Franklin – steel guitar ; Rob Hajacos – fiddle ; John Hobbs – Hammond B-3 organ ; Bobby Huff – acoustic guitar, keyboards, drums, percussion ; John Jorgenson – electric guitar ; Paul Leim – drums ; B. James Lowry – acoustic guitar ; Randy McCormick – piano, keyboards, Hammond B-3 organ ; Terry McMillan – harmonica ; Dale Oliver – electric guitar ; Danny Parks – acoustic guitar ; Larry Paxton – bass guitar ; Buck Reid – steel guitar ; Randy Threet – bass guitar ; Jason West – bass guitar ; John Willis – electric guitar ; Bob Wray – bass guitar As listed in liner notes.
Title: Squad Five-O
Content: Jeff Fortson - Vocals, guitar (1997–2006) ; John Fortson - Bass (1997–2006) ; Adam Garbinski - Guitar (1999–2006) ; Kris Klein - Guitar (2000–2006) ; Dave Petersen - Drums (2001–2006) ; Justin Kohut - Drums (1995–1997) ; Jason Anderson - Drums (1997–2000) ; Justin Garbinski - Drums (2000–2002) 
Title: 6 (The Ex album)
Content: Andy – guitar, violin ; G.W. Sok – vocals ; Kat – drums, steel drum ; Luc – bass, double bass ; Terrie – guitar Brader Mûsîkî – vocals and saz on 6.2 ; Jeroen – sounds on 6.2 and 6.4 ; Han Bennink – drums on ''6.4' ; Ab Baars – saxophone and clarinet on 6.4 ; Wolter Wierbos – trombone on 6.4 ; Colin McLean – bass guitar on 6.4 ; Marion Coutts – trumpet on 6.4 ; Wilf Plum – drums on 6.4 ; Dorpsoudste de Jong – poetry on 6.4 ; Herr Seele – flute, mandolin and violin on 6.4 and 6.5 ; Johan De Smet – piano and organ on 6.5 ; Kamagurka – vocals on 6.5 The Ex Guests
Title: Five for Freddie
Content: Bucky Pizzarelli – guitar, leader ; Warren Vache – cornet ; John Bunch – piano ; Jay Leonhart – double bass ; Mickey Roker – drums 
Title: 44 &amp; 66
Content: Greg Brown – vocals, guitar ; Chuck Henderson – guitar ; Dave Moore – harmonica ; Ron Rohovit – bass ; Al Soucek – clarinet ; Prudence Johnson – background vocals ; Gary Delaney – mandolin 
Title: Gypsy '66
Content: Gábor Szabó – guitar ; Sam Brown – guitar ; Barry Galbraith – guitar ; Sadao Watanabe – flute ; Richard Davis – double bass ; Albert Stinson – double bass ; Grady Tate – drums ; Gary McFarland – marimba ; Chino Pozo – percussion ; Willie Rodriguez – percussion 
Title: Combo 66
Content: John Scofield – guitar ; Gerald Clayton – piano, organ ; Bill Stewart – drums ; Vicente Archer – bass ; Jay Newland - record and mix engineer 
Title: Five Year Mission
Content: Noah Butler - Lead vocals, guitar, bass guitar, backing vocals and keyboard. ; Andy Fark - drums, lead vocals, and backing vocals ; Patrick O'Connor - Lead vocals, guitar, bass guitar, backing vocals and keyboard ; Mike Rittenhouse - Lead vocals, guitar, bass guitar, backing vocals and keyboard ; Chris Spurgin - Lead vocals, guitar, bass guitar, backing vocals and keyboard 

Question: who played lead guitar on 25 or 6 to 4?
Answer: Terry Kath.