What was the B-side to 'Stairway to Heaven'?

Stairway to Heaven was released on Led Zeppelin's untitled fourth album commonly referred to as Led Zeppelin IV on November 8, 1971.

The track listing is as follows:

Side one
"Black Dog" (Page/Plant/Jones) – 4:55
"Rock and Roll" (Page/Plant/Jones/Bonham) – 3:40
"The Battle of Evermore" (Page/Plant) – 5:38
"Stairway to Heaven" (Page/Plant) – 8:01

Side two
"Misty Mountain Hop" (Page/Plant/Jones) – 4:39
"Four Sticks" (Page/Plant) – 4:49
"Going to California" (Page/Plant) – 3:36
"When the Levee Breaks" (Page/Plant/Jones/Bonham/Memphis Minnie) – 7:08

So I believe the answer you are looking for is the tracks on side two of Led Zeppelin IV. Stairway to Heaven was never released as a single.

https://en.wikipedia.org/wiki/Led_Zeppelin_IV#Track_listing
https://en.wikipedia.org/wiki/Stairway_to_Heaven

Neil Sedaka 45 rpm
Stairway to Heaven, 7" Vinyl,
A Side: STAIRWAY TO HEAVEN,
B Side: FORTYWINKS,
Away label: RCA 47-7709,
Year Released: 1960
https://www.discogs.com/Neil-Sedaka-Stairway-To-Heaven/release/6209332

Okay, you're probably not looking for that one. As any rock fan should know, "Stairway To Heaven" was never released as a single.

7 INCH 1990 Reissue (for promo use only)
A Side - STAIRWAY TO HEAVEN
B Side - WHOLE LOTTA LOVE
On ATLANTIC Label
https://rarerecords.com.au/store/vinyl/stairway-heaven-whole-lotta-love/

The (Runes, 1971) album also featured "Stairway to Heaven", which became a massive album-oriented rock FM radio hit despite never being released as a single.
https://en.wikipedia.org/wiki/Led_Zeppelin

The year on that 45 I found, 1990, made me suspect, but I found another source that it exists, but only 150 copies, so is very rare.

http://www.vjez.com/zep/default.asp?pagina=uk45

Actually there was another disk put put out..its a picture disk with Robert plant and jimmie page playing live. There is no label stairway is on one side and hey hey what can i do is on the other. Very rare. I own a copy