Grosset & Dunlap purple/white spine formats

I'll admit, as of now I'm lumping a few formats into one.  James Keeline (correctly) separates these out into different formats.  There were variations, as James shows on his page (listed under Further Resources). 

Although all titles still in print in the '70s were eventually available with this purple/white spine, the earliest printings of #71 and #72 were not printed in this format until the (mid-'80s)--originally they were published with solid purple spines, as seen on the Solid-Purple-Spine page. 

James Keeline provided this list he made up regarding these printings--which ones were printed in this format, and other characterisitics about them:

Any blank spots below are simply because I don't have the book in my collection.  If it has a spot below, it *does* exist. 

There is also an oddity that I just came across--don't know how widespread it is:  This is a copy of Sun Moon Cruise without the number on the spine. 

Below in the full list is another oddity: #67 without a number on the front cover.

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1st format picture-cover rear cover

Glossy cover stock. Probably the last format to be printed.

#1

#6

#11

#16

#24

#43

#48

#53

#58

#63

#67 WITH # on cover

#72

#2

#7

#12

#17

#25

#44

#49

#54

#59

#64

#68

#3

#8

#13

#18

#27

#45

#50

#55

#60

#65

#69

#4

#9

#14

#19

#38

#46

#51

#56

#61

#66

#70

#5

#10

#15

#20

#42

#47

#52

#57

#62

#67 WITHOUT # on cover

#71