New to this forum so please bear with me while i try and figure out how this works. The reason i am here to to hopefully identify a part. I got in my 03 dodge tam 3500 and when i turned the key over it started making a loud clunking noise coming from just behind the passenger side battery. It makes this noise wether the truck is running or just in the starting position. I managed to find what was making the noise but have no idea what the part is called. Hopefully i can attach my pictures and get some answers

 

Ty, it looks like a vapor canister to me.
Let us know your engine and others with same setup will chime in.