I always liked TR6's Jim.
Although pictures would help and a bit more description.
Essentially your Luger breaks down into;
S/42 equals made by Mauser
On the top of the barrel (actually the receiver?)it is marked 1936, then that would be the year
Import marks show it was brought into the country by Miltex, others will know more
If you can describe the eagle proof marks? Go to the left of this website
www.lugerforum.com and there will be an area called technical and you will find proofs and marks and if you could tell us the one that looks closest to the number, we can help you.