how many times are you going to change the name of this thread? lol. Three that I've counted...
Anywho, the 2186 is the same saw as the 385. I had one and used 385 parts to fix it up. Good running saw. Lots of power, but feels as heavy as an 066 to me. that is why i sold it. I found that i grabbed the 066 more because they were so close in weight and it had more azz.
But if you never ran the other, the 2186/385 is a great saw. Mine normally had a 24" on it for hardwoods.
The 7900 is a lot lighter and has the same power up to the 24-28" range. After that, I can't tell you as i didn't run longer bars on either of them.
And they both share the same bar mount (oregon D009).