Question about heater hose at back of block
 

Hokay so,

I have a question which I think I may have the correct answer to already, but just in case...

In the picture with the two hoses, above is the new UPDATED part and below is the older original part. Please notice that in the new part the connector for the top metal pipe is missing, this pipe goes back to the top of the coolant reservoir.

So, when I replace the old piping with the new piping, I would also install the new white coolant tank as well right?

By doing this I am bypassing the topmost metal pipe that runs along the back wall of the engine bay... (I could remove this excess pipe later, but for now will bypass...)

Am I correct?

I believe your original setup is the updated version. That black metal chamber was added to attempt to get air out of the heater system that caused a gurgling sound. If you try to order a replacement hose, they send you the assembly that you have pictured and you have to cut the hoses.
Later W124's had a modified heater core that did not have the gurgling problem.

Okay, thank you for your help, makes perfect sense now.