Just bought this and instantly hearing crunching/rattling style noises when in low gears moving slowly. Took into mazda they say this is normal noise from this model. Anyone here able to shed some light on this for me.

 

What one thread was not enough about this subject from you? Go to a shop that specializing in drivetrains like a Transmission Service shop. Or a Mazda dealership that has a Mazda certified factory trained mechanic Anything less and forum members guess is not going to solve or exactly answer your question. This type of concerns really needs to have the vehicle present to at least determine if a noise you think is normal or not.
Or go read the response in your other thread you asked the same question on!