[G4] G4 Processors, how interchangable?

[Matt Pendergast]

How interchangeable are the different G4 processor cards. For example 
could I snag a 733mhz and put it in my Sawtooth despite the different 
bus speed? It should run slower if it ran at all. How about physical 
interference within the case? Voltage differences? How about the socket 
itself does it change from family to family or are they the same for all 
G4's?
Thanks in advance!
Matt