I downloaded a 1974 Douglas County map from the KDOT site, and it shows K-10 heading north on US 59 at 23rd and Iowa. There are no K-10 shields west of US 59. Did K-10 end at US 40, did it follow McDonald Drive to the turnpike, or is this just a remnant from when K-10 followed today's US 40 to Topeka?
The maps are at:
http://www.ksdot.org/maps.asp
Go to the Past Published County Maps page:
http://www.ksdot.org/burtransplan/maps/PastPublishedCounty.asp
Until the western leg of the SLT was completed in 1996, K-10 followed Iowa Street (US 59) north from 23rd to 6th Street [I never took a picture of the sign assembly, but I can most assure you that there was a END K-10 assembly at 6th and Iowa.