hello and welcome, indeed the best thing to do in general when using this site is to use its very large archives.
Once you do that it will be advisable to continue an existing thread because this gets you MORE rather than less attention to any particular subject since it will be published anyway in the new active threads AND it will automatically send an alert to all the people whom have previously partaken to the thread on that subject.
The Dearman saxophones were certainly all stenciled.
Many would be Italian made ( but I think that yours is NOT), this one that you are linking may or may not be one of those but the pictures that you are offering are insufficient to make a certain identification. The manufacturing year, will be, at best a guess even if we know for sure who made it because few of these brands kept records that were exact.
https://forum.saxontheweb.net/showthread.php?218336-Shortcomings-of-Dearman-Alto-Sax
MY best Guess is that this is a Kohlert or a Franz Kohler
https://forum.saxontheweb.net/showthread.php?161987-Mystery-Alto-Can-Anyone-ID-This-Instrument-gt made horn from the ’50. The value is not huge and largely what you want to give for it. There isn’t a special market for any of these horns and I have seen them going for anything from €100 to a maximum of €350, it may be worth slightly more if it weren’t a stencil and had a better known brand on it.
Indeed if the horn needs an overhaul you may ask yourself if your money will not be better spent on something else since its cost may raise to anything from €300 to €700 for the overhaul itself but its commercial value would be marginally affected by the added overhaul.