One Life to Live - 1968 1-10042 was released on:

USA: 17 October 2007

Days of Our Lives - 1965 1-10042 was released on:

USA: April 2005

Belgium: 13 October 2009

10,042 miles = 16,161.0324 kilometers

Gilbert Erector Sets were made for decades (1913 to 1967) and in many sizes, so there is on one simple answer to your question. Since there were many small parts (to say nothing of the many screws and nuts one used to put your creations together), it is rare to find one with all of its parts. The more complete a set, and the better the condition, the more value. Sets can be had for as little as $10, and as high as $900. The $900 sets are, of course, seldom found! For many years sets were numbered from #1 to #12, then in 1956 A C Gilbert Co. went to a computerized inventory system and 5 digit numbers (example 10042, the Radar Set). The metal boxes also went from a solid color (usually red) metal case to one with color graphics depicting an assembled model. This might help you date your set.