Hello Michael!

  MT> The DIN connector specification is only for Germany.
    > If you want to be truely accurate the connectors are
    > IEC 603-2 Type C-96.

Are they mechanically and functionally the same?

  MT> The 3/50 and 3/60 only get power from the connector.

The more I read about 3/60 mainboards the more I want one!
:-)

  MT> The 9U Sun boards have conventional 32-bit VMEbus on
    > the a, b, and c rows of the J1 (left) and b row of the
    > J2 (middle) connectors.  There is a proprietary Sun
    > memory bus on the a and c rows of the J2...

This was my first guess, with the SUN proprietary bus on
the 'user defined' rows of J2/P2.

  MT> ...and the b row of the J3 (right) connectors of CPU,
    > Memory, some Video, Z-Buffer, and Graphics Processor
    > boards. The a and c rows of the J3 connector have
    > additional power pins.

This is a blatant guess, but are the additional power pins
in the same place on the connector as those for J1/P1?  I'm
guessing this means the b row of J3/P3 is segmented as per
J2/P2, with the power bus running right the way along.  Does
this sound about right?

Regards,
  - Andy.