xserve power supplies

Are Intel xServe (2006, 2008, 2009) power supplies interchangeable? E.g. 2008 and 2009 xServe have very similar PSUs (750W) - can they be swapped across models?

What are the part numbers of these PSUs? xServe Tech Specs list Apple part numbers (such as MB090LL/A) but not, say, 661-4650 or 614-0437, etc.

Thanks!