Now to explain the 6/29/1974 show scheduled to air this weekend.
It is one of two original Casey-hosted AT40 shows in which an incomplete Billboard chart ran (6/9/1973 when the Hot 100 was revamped was another). For this show, the AT40 staff tried to guess what Billboard's Top 40 would look like in advance of the actual chart as Casey Kasem was about to depart for a few weeks to tape a guest appearance on "Hawaii Five-O". In the end, they got three out of 40 (the top two plus #34) correct.
Here was the actual Billboard chart for 6/29/1974 (AT40 positions in parentheses)
LW TW
03 01 Gordon Lightfoot - Sundown (1)
01 02 Bo Donaldson & The Heywoods - Billy, Don't Be A Hero (2)
02 03 The Stylistics - You Make Me Feel Brand New (4)
05 04 William DeVaughn - Be Thankful For What You Got (3)
07 05 Olivia Newton-John - If You Love Me (Let Me Know) (7)
12 06 The Hues Corporation - Rock The Boat (5)
09 07 Kool & The Gang - Hollywood Swinging (8)
06 08 Paul McCartney & Wings - Band On The Run (10)
15 09 George McCrae - Rock Your Baby (6)
27 10 John Denver - Annie's Song (16)
21 11 The Hollies - The Air That I Breathe (13)
16 12 Anne Murray - You Won't See Me (23)
17 13 Gladys Knight & The Pips - On And On (11)
04 14 Ray Stevens - The Streak (9)
19 15 Mac Davis - One Hell Of A Woman (18)
08 16 Jackson 5 - Dancing Machine (12)
25 17 Steely Dan - Rikki, Don't Lose That Number (20)
20 18 The Spinners - I'm Coming Home (19)
24 19 The Righteous Brothers - Rock And Roll Heaven (14)
26 20 Blue Magic - Sideshow (26)
11 21 Maria Muldaur - Midnight At The Oasis (22)
10 22 Marvin Hamlisch - The Entertainer (25)
13 23 The O'Jays - For The Love Of Money (15)
14 24 Carly Simon - Haven't Got Time For The Pain (17)
28 25 Ozark Mountain Daredevils - If You Wanna Get To Heaven (27)
18 26 The DeFranco Family - Save The Last Dance For Me (21)
31 27 Cher - Train Of Thought (24)
22 28 Jim Stafford - My Girl Bill (31)
40 29 Golden Earring - Radar Love (28)
39 30 ABBA - Waterloo (29)
23 31 Joni Mitchell - Help Me (32)
34 32 The Eagles - Already Gone (30)
29 33 Grand Funk Railroad - The Loco-Motion (39)
DE 34 Elvis Presley - If You Talk In Your Sleep (34)
DE 35 The Impressions - Finally Got Myself Together (I'm A Changed Man) (37)
32 36 Three Dog Night - The Show Must Go On (NR)
DE 37 Bachman-Turner Overdrive - Takin' Care Of Business (35)
30 38 Cat Stevens - Oh Very Young (NR)
DE 39 Jim Croce - Workin' At The Car Wash Blues (36)
DE 40 Jimmy Buffett - Come Monday (38)
The two songs AT40 guessed that didn't make the actual chart were (actual Billboard positions in parentheses)
33: ZZ Top - La Grange (41)
40: Wet Willie - Keep On Smilin' (44)
"Keep On Smilin'" would eventually hit the Top 40 the following week and eventually peaked at #10. As for "La Grange", unfortunately #41 would be its' peak but it continues to be a staple on classic rock stations.
Here are the optional extras for this week's show
Hour #1: "The Night Chicago Died" - Paper Lace (#74)
Hour #2: "Rock Me Gently" - Andy Kim (#66)
Hour #3: "You And Me Against The World" - Helen Reddy (#63)