It is an 056 the 6 is just scratched out in a way that it looks like a 5, but is different from the real 5.
Stuff gets miss listed on CL a fair amount, like the 311y listings that pop up on occasion. The 046 I have was improperly listed as a MS 650.
If you are tempted to buy it check for spark. If it has none, leave it where it is unless you love to spend money.
I'm not gonna buy it lol. I was just checking out saws and hadn't heard of this one. I'm not familiar with Stihl so thought I'd ask.