The early 044 had 10 mm wrist pins in the pistons instead of 12 mm. As a result, with less weight they respond faster. There is also some hearsay (I'm not sure if it is true or not) that they may have had higher compression and/or freer flowing mufflers. The consensus is that the 10 mm saws run a little stronger even though they were only rated at 5.1 Hp and subsequent 044/440s were rated at 5.4.
Bottom line is they are all great saws. I believe the 10 mm has the angled fins, may have a red (instead of black) control lever, and mine does not have compression relief. If you go to Baileys on line and look at their pistons and big bore kits they will give you the serial # when the change occurred, but again different sources sometimes give different #s.
If you got a good price and your saw is in good shape you have a "classic" and a very good saw. I would not be concerned about the rest of it.