That's not right. WHAS/WAMZ has been #1 and #2 every book since sometime in 1985 or earlier.
WRKA was #1 in 1 book at some point- 83 or 84. I wasn't around. (I was out of the market from 79-86)
If DJX made it to number 1 it was in the early 80s.
WLOU had a number one book around 82 or 83 then RKA had their number one book. Beyond that it has been WHAS and WAMZ. I seem to remember WVEZ spiking to number one in 1980 with WAKY having their last up and good book was in second place. Gleason's history site have the old Duncan books with numbers for more details.