Here is a link to a free B757 from just flight that is now being released as freeware
https://www.justflight.com/product/757- ... r-freemium
The engine sounds are very realistic. It does have a FMC but it is not a fully working model. You can import FSX flight plans into it.
It also has a working TCAS that will display traffic a decent 3d virtual cockpit and some good 2d views as well
For free you can not beat it. It handles real good