Questions about dual-motherboard cubes

Here is what appears to be a cube configured with two '040 (non-turbo?) 
motherboards.  I remember reading that doing this with an '030 and an 
'040 requires a backplane modification.  Is the backplane modification 
still required when two '040 boards are used?

In such a configuration, are all the on-board devices available from the 
NeXTbus? [if there is any good documentation on the memory map, please 
direct me to it]  If so, wouldn't this mean that it would be possible to 
use the machine for SMP if the OS could take advantage of this?

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=2042712505&sspagename=ADME:
B:SS:US:1

Thanks,
-Tim