Yup, this SML was made by Dörfler & Jörka in Nauheim, Germany. D&J was a company that had a long and complicated relationship with J. Keilwerth. I have
the company's history on my website, as it was recently published in the German music journal:
Sonic Sax & Brass. The article's author, Uwe Ladwig, conducted research last year to find out what he could, about this former German saxophone manufacturer that was renowned for making J. Keilwerth copies.
In the beginning D&J did use J. Keilwerth body tubes and attach their own keys (built to Keilwerth specs). However, after approx. 18 months (in 1950) the orders from Keilwerth dried up. At that point D&J went on to manufacture their own saxophones that were J. Keilwerth copies. These horns were not 100% identical to the Keilwerths however: there were some pretty major differences in the necks and body tubes.
In 1965 J. Keilwerth took over the manufacturing facilities of D&J, and in 1968, the company was officially shut down, and Dörfler went to work for J. Keilwerth again. (He had started his career with J. Keilwerth in Graslitz.)
So far I have managed to come across 24 different stencil names that D&J built their saxophones under. I suspect there are many more.
This was just a really quick and dirty overview of the company's history. I've left out lots, including the D&J vs. J. Keilwerth court case, etc. All of what I didn't talk about here, is on the
D&J page on my site, as are lots of pictures, and info on the the differences between the 2 brands of horns.
Hope this helps.