Willys-Overland began publishing the Salesbuilder magazines in July of 1948 with the announcement of the Jeepster. The Salesbuilder supplanted the W-O Sales News magazine. According to a small blurb on Google (I can’t read the whole reference), the Salesbuilder was part fo the effort to push the Jeepster.
I own a couple of Salesbuilder magazines, but those are the only ones I’ve seen. Below is a series of covers that I’ve been able to document so far. I’d like to find more.
As far as I know, Salesbuilder issues were published between July of 1948 and as late as August of 1951. By early 1954 (possibly January), Kaiser Willys had shuttered the magazine format for a newspaper format (see the March 1954, volume 1, issue 2 at the bottom of this post).
July 1948:
November 1950: