Do you love Joni? Did Joni's music change your life? Then this is the subreddit for you.
archive.org/details/at-40-6-8-74-jun-14
...and by now you probably know: archive.org let's ya stream or download. Feel free to scroll around the grounds.
CASEY KASEM'S AMERICAN TOP 40 – June 8th, '74 (Note: The program actually starts around 7 minutes in, and it ends well before the 3.5 hour mp3 ends. Hey I only report these things; I don't upload 'em...)
40: SIDESHOW – BLUE MAGIC
39: NO CHARGE – MELBA MONTGOMERY
38: RIKKI, DON’T LOSE THAT NUMBER – STEELY DAN
37: IF YOU WANNA GET TO HEAVEN – OZARK MOUNTAIN DAREDEVILS
36: THE PAYBACK (PART 1) – JAMES BROWN
35: THE AIR THAT I BREATHE – THE HOLLIES
34: COME AND GET YOUR LOVE - REDBONE
33: MIGHTY MIGHTY – EARTH, WIND & FIRE
32: ANOTHER PARK, ANOTHER SUNDAY – DOOBIES
31: SON OF SAGITTARIUS – EDDIE KENDRICKS
30: I’M COMING HOME - SPINNERS
29: ON AND ON – GLADYS KNIGHT & THE PIPS
28: ONE HELL OF A WOMAN – MAC DAVIS
27: TSOP - MFSB
26: BENNIE & THE JETS – ELTON JOHN
25: JUST DON’T WANT TO BE LONELY – MAIN INGREDIENT
24: SAVE THE LAST DANCE FOR ME – DeFRANCO FAMILY
23: (I’VE BEEN) SEARCHIN’ SO LONG - CHICAGO
22: DON’T YOU WORRY ‘BOUT A THING – STEVIE WONDER
21: HAVEN’T GOT TIME FOR THE PAIN – CARLY SIMON
20: YOU WON’T SEE ME – ANNE MURRAY
19: I’M IN LOVE – ARETHA FRANKLIN
18: I WON’T LAST A DAY WITHOUT YOU – CARPENTERS
17: HOLLYWOOD SWINGING - KOOL & THE GANG
16: THE SHOW MUST GO ON – THREE DOG NIGHT
15: IF YOU LOVE ME – OLIVIA NEWTON-JOHN
14: THE LOCO-MOTION – GRAND FUNK
13: OH VERY YOUNG – CAT STEVENS
12: MY GIRL BILL – JIM STAFFORD
11: BE THANKFUL FOR WHAT YOU GOT – Wm. DeVAUGHN
10: FOR THE LOVE OF MONEY – THE O’JAYS
9: MIDNIGHT AT THE OASIS – MARIA MULDAUR
8: THE ENTERTAINER – MARVIN HAMLISCH
7: HELP ME – JONI MITCHELL
6: BILLY, DON’T BE A HERO – BO DONALDSON / HEYWOODS
5: SUNDOWN – GORDON LIGHTFOOT
4: DANCING MACHINE – THE JACKSON 5
3: YOU MAKE ME FEEL BRAND NEW – THE STYLISTICS
2: THE STREAK – RAY STEVENS
1: BAND ON THE RUN – PAUL McCARTNEY & WINGS
(Edit: Casey's Joni intro starts at about 2:05:40 I think, although it's probably more interesting to hear individual songs on AT40 in the context of what's before and after.)