Question: Lindsey Buckingham and Dallas Taylor both fulfill which identical role in each of their respective acts?

Context paragraphs:
Love in Store: "Love in Store" is a song by British-American rock group Fleetwood Mac.  The song is the opening track on the 1982 album "Mirage", the fourth album by the band with Lindsey Buckingham acting as main producer with Richard Dashut and Ken Caillat.  "Love in Store" was written by Christine McVie and Jim Recor and it became the album's third single in the US.  Released in November 1982, it went on to peak at No. 22 for three weeks as the follow-up to Top 20 hits "Hold Me" (No. 4) and "Gypsy" (No. 12).  The song features lead vocals by Christine McVie with prominent vocal harmonies by Stevie Nicks and background vocals by Lindsey Buckingham.

Oh Diane: "Oh Diane" is a song by British-American rock group Fleetwood Mac.  It was written by guitarist Lindsey Buckingham and Richard Dashut, for the 1982 album "Mirage", the fourth album by the band with Lindsey Buckingham as producer.

Lindsey Buckingham/Christine McVie: Lindsey Buckingham/Christine McVie (also referred to as simply Buckingham/McVie) is a studio album by Fleetwood Mac vocalists Lindsey Buckingham and Christine McVie, released on June 9, 2017.  Four of the five members of Fleetwood Mac are featured in the album, with contributions from drummer Mick Fleetwood and bassist John McVie.  Vocalist Stevie Nicks is the sole member absent in the album.  The album sold over 22,000 units in the US in its first week and debuted within the top 20.  It proved to be even more successful in the UK, where it debuted within the top 5.

Buckingham Nicks: Buckingham Nicks is the sole studio album by the American rock duo Buckingham Nicks.  Produced by Keith Olsen, the album was released in September 1973 by Polydor Records.  "Buckingham Nicks" is notable as an early commercial collaboration between Stevie Nicks and Lindsey Buckingham, both of whom later joined Fleetwood Mac.  The album was a commercial failure on its original release, and despite the duo's subsequent success, it has yet to be commercially remastered or re-released on any format since 1973.  The rights are now with the former couple as the original company Anthem (not the Canadian label of Rush fame) has long since become defunct.

Go Insane (song): "Go Insane" is the title track of Lindsey Buckingham's second solo album.  Released as a single, 3 July 1984, it became Buckingham's second top 40 hit (after "Trouble", three years earlier).  "Go Insane" is also Buckingham's most recent U.S. solo hit (peaking at #23 in the "Billboard" Hot 100 chart); on the other hand, it did not chart in the United Kingdom.

Out of the Cradle: Out of the Cradle is the third solo album by the American singer/songwriter Lindsey Buckingham.  Released in 1992, it was Buckingham's first album after his much-publicised departure from Fleetwood Mac in 1987 (though Buckingham rejoined the band in the mid-1990s).  The album reached #128 on the US "Billboard 200" album chart, #51 on the UK Albums Chart, and #70 on the Canada Albums Chart.  In Canada, three singles charted within the Top 60.

Sinai 48: Sinai 48 is an American band formed in 2006 consisting of Alex Helene (vocals), Ananiah McCarrell (guitars and synthesizers), Gary "Hoppy" Hodges (drums and percussion), and Tom Moncrieff (bass and digital editing).  The latter two were formerly members of the band Buckingham Nicks with Lindsey Buckingham and Stevie Nicks.  Sinai 48 is the first reunion of the other band members since Buckingham and Nicks joined Fleetwood Mac.

Lindsey Buckingham: Lindsey Adams Buckingham (born October 3, 1949) is an American musician, singer, songwriter, and producer, best known as lead guitarist and one of the vocalists of the musical group Fleetwood Mac from 1975 to 1987, and then 1997 to the present day.  Aside from his tenure with Fleetwood Mac, Buckingham has also released six solo albums and three live albums.  As a member of Fleetwood Mac, he was inducted into the Rock and Roll Hall of Fame in 1998.  In 2011, Buckingham was ranked 100th in Rolling Stone Magazine's 2011 list of "The 100 Greatest Guitarists of All Time".  Buckingham is known for his fingerpicking guitar style.

Dallas Taylor (vocalist): Dallas Taliaferro Taylor (born May 17, 1980) is an American musician who is the vocalist for the Southern metal band Maylene and the Sons of Disaster.  He is the former vocalist and founder of the American metalcore band Underoath.  He performed on three Underoath albums: "Act of Depression", "Cries of the Past", and "The Changing of Times".  In 2003, Dallas left Underoath, and was replaced by Spencer Chamberlain.  He was born in Ocala, Florida.

Say You Will (album): Say You Will is the seventeenth studio album by British-American rock band Fleetwood Mac, released on 15 April 2003.  It was the first Fleetwood Mac album since "Kiln House" in 1970 that did not include tracks written by vocalist/keyboardist Christine McVie, who had left the band in 1998.  It was however the band's first studio album since "Time" was released in 1995.  Members Lindsey Buckingham, Stevie Nicks and John McVie shared keyboard duties for the album, though Christine McVie is featured on two songs which had been originally recorded for an unreleased Lindsey Buckingham solo album (tracks 13 and 14).  It also marks the first album in 16 years to feature Buckingham as a full time member.

Supporting paragraphs: Dallas Taylor (vocalist) Lindsey Buckingham
Answer: vocalist