For Poulan's current offerings, if you cross reference the part numbers for the jug and piston, you will find that the parts are also used in many of the other saws under 50cc. The crank may change a bit but that's mainly due to the clutch end of the shaft (inboard/outboard clutch). For example, they bill the PP3314 as a 33cc saw, but if you look at the EPA sticker, it states that it is a 42cc class engine. The piston and jug cross reference to the same ones that are also used on the PP4218, my PP3516, the 4016, and many of the Sears/Craftsman saws.
Like anything else, if you use it within its design limits and care for it well, it will last you many years. If you treat it and maintain it like a cheap throw-away, it will be thrown away in a few years. Don't expect to take down the mightiest tree in the forest. It's not designed for that.