If it was made in Wetzlar it will have a promiment engraving on top "Ernst Leitz Wetzlar GmbH" like in this picture http://i10.ebayimg.com/01/i/04/42/a5/81_1_b.JPG and the logo will say "Leitz". Solms-Leicas have plain tops and the logo will say "Leica". If I were you I would choose a Solms-M6 over a Wetzlar-M6 any time as the former have updated electronics which have some weakpoints eliminated and their reliability enhanced. Furthermore, the sensitivity is 2 stops higher than in the Wetzlar M6 further enhacing your available-darkness capabilities. It is said that some parts are made from lesser materials (die-cast non-adjustable instead of brass multi-part adjustable) but honestly, as a user, I don't care. I would suggest that collectors should stick to their M2s M3s, M4s and M5s and leave alone that humble, modern M6.
Originally Posted by Frank Petronio