....There is both an EGR valve and a separate "EGR Modulating Valve".

I was looking at this in the FSM, and it stated if anything went wrong with the electrical part of the EGR, it would go to full vacuum all the time.

On my old EGR assembly, the electrical was fine, it was the EGR itself that was bad, leaking diaphragm?

At this point, if not anything else, I fixed a vacuum leak I didn't realize the truck had. I continue to be amazed how much better the truck idles and runs now. I thought it ran fine before, but, often at idle, it sounded 'blubbery' (is that a term?) It lacked a 'crispness' if you will.

Now that blubbery' sound is gone, and its smoother than it was before.

I did the on-off key test to pull codes, and it only showed '55'.

Thank you 360view for that lengthy response.