Ryan, I did a seach and came up with mote than 40 answers - in one of them Gary Drye replied this:
"This is taken from a PCM article on the signs.
From roughly 1926-1935 the signs were 8" x 7". From 1935 to the '70s the 6" x 7" were used. From 1925-35 these signs were available in flat or curved versions. Also, water transfer decals were used during this time period.
An example is given for a Wayne #615 visible and the article suggests the longer sign with the extra writing about "avoid spilling".
I have had many of the short Gulf pumps from the early 1960's and everyone of them has the "anti-knock compounds" lettering. So I assume these are later versions."
regards,
Claes