What is the importance of runnablility to have the EGR functioning?

Mine is rotted out and need to know if it will be worth my time or money to replace it...

I have completely replaced the exhaust on my campmobile, less the EGR filter itself (mine is rotted out and the pipe connecting to the muffler is gone)... Is it worth the US$100 I have found it for?

does it effect the engine in any manor or simply another part to replace with no ill effect on the engine runability or life?

Let me know and I'll get one if it's a needed part...

thanks.

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1977 Westfalia Campmobile

New paint, new exhaust system, replacement H4 headlight conversion, new tail light assemblies, JVC CD player, Infinity 6.25 and pioneer 6x9's...