I thought I'd include this quote because it describes my situation perfectly. I have had a single processor 2009 cMP for over a year now, and saw a great deal on a dual tray 2009 and picked it up as well.People buy Dual Processors Macs just to get the tray. Usually they keep the best parts of the Macs and resell the single tray one to keep the costs down.
Other than cosmetics and the tray, what would be the best way to determine which components to keep? Obviously I'm keeping my dual cpu daughterboard. I've looked up manufacturing date on my motherboards boards, one was produced in the USA in April 2009 and the other was produced in China in December 2009.
Are there any components or chips that on the motherboard that were sourced by multiple suppliers, and are there preferred suppliers? Any good way to decide what power supply to keep? Any way to determine lifetime uptime or important capacitors or traces to inspect?
P.S. If there is reason to prefer 2010 or 2012 models, or any other discrepancies between seemingly similar Mac Pro's, maybe this could be a place to discuss such things.