Thanks - that was helpful and worked - just what I needed!
The reason why I need to change the Duration to "months", and to help you understand my perspective, the Master Schedule I'm developing will be used in a proposal in response to a Request For Quotes (RFQ).
I need the Master Schedule to be EASILY interpreted by people unknown to me who will read it. If they have to stop and try to figure out why the # of Days doesn't jive with the # of months then I've lost before I even got started......
My effort with the Master Schedule is to show a high-level Program Plan and an estimate of how long the entire project will take.