How old and how much?

I have a pretty ancient Martin Alto. Could anyone tell me how old it could be? I've been playing it for about 8 and a half years now and I'm in love with it...
I'll try to post a picture later.

-Very little Lacquer is left on it...If I hade to guess, I'd say 25-35% at most.
-Adjustable thumb rest
-Serial number: 178721
-It's in really good condition. There's a tiny dent in the base of the bell and a scratch or two here, but otherwise it's fine.
-The neck is...Very odd. It doesn't have those two prongs on either side of it that's supposed to keep it straight. (I have to be very careful with the neck...The person who fixes my saxes says he probably wouldn't be able to replace it if it were to break.)
-The octave hole on the neck is flat, not rounded like modern horns.
-The low Eb key is a little weird. It's not completely covered like most horns, so when I play in bewteen my knees, it's difficult to play Eb because the key won't go up.

There's too many other peculiarities about this horn to list, but hopefully that's enough for now. I'll post a picture later when I have a chance.