The 046 was introduced in 1996, and has been a reputable saw ever since. The saw underwent some modifications in 2000, consisting of a widened intake port, additional openings in the filter mounting base, and an increase to 6.0 hp. In 2002, with the advent of the MS460 came an improved conrod big bearing end, which allowed for better lubrication. And like oldsaw mentioned, the 046 became the MS460. As far as what they're worth, that's a toughie. There's new in box 460 Mags on ebay going for $625+, and older 046's going for $300. A full wrap handlbar will usually fetch a bit more, as will a new bar and chain. These are pro saws, and if you can find one that was owned by a homeowner, and used as such, you'd have a saw with more time left on it than one used hard by a pro every day in tough conditions. Parts are however readily available for these saws, so rebuilding one is also an option if you're comfortable with a wrench. What would you use the saw for? They're a big, pro saw, and if firewood is your only concern you could do just as well with less weight, and less $$ if you looked at an 036/360 for example. That said, many of us do use them for firewood, though I enjoy using my 361 more, and it's easier on my back! Just a thought.
And welcome to the forum. I think you'll find a wealth of knowledge and info here.
Take care all,
Jeff