Well I just picked it up! Must have looked pretty funny riding around the gas station parking lot in cowboy boots and on an old Schwinn to boot (pun intended)! Well worth the $75 IMHO.
Anyway, mine only has three numbers (356), and it's on the right-hand side of the head badge. Also, the head badge doesn't look exactly like your picture in that it doesn't say Japan, just the 6-something number that is apparently the Chicago zipcode of Schwinn. If it helps, it's a 25" Traveler (best I can tell by the largely missing top tube decal), is fire-engine red and white two-tone (the headtube is white and a portion of the seattube), and came with center-pull dia compe brakes, a Shimano FE front derailer, a Shimano 400 rear derailer, a 5 speed cassette, and the rear serial number is 2347224. (link to Craigslist ad here
http://dayton.craigslist.org/bik/736463415.html).