I replaced mine on our 2006 Newmar Essex a couple of years ago. Easy job! The EGR is very accessible; Look above and to the right of the alternator. EGR valve was pretty cheap as I recall.
BTW: The Ugly Fix (not ugly valve) was a pain in the a$$ to install on my ISM. It was taped up, painted Cummins red and buried way up in the wiring harness on the intake side of my engine. It replaces a barometric sensor and tricks your engine into thinking it is at high altitude and prevents the EGR valve from opening and allowing exhaust gas to flow. I tried it and also threw an engine fault code, so I removed it and put the original sensor back in.
Ron & Laureen Ramsey
2019 Newmar Mountain Aire 4551