I plugged in the ribbon cable & a power cable into their respective slot 4 positions.
I changed the number of miners from 24 to 32.
The holes that attach the heat sink to the bottom place are not compatible.  I affixed 1 screw to the heat sink, and tried not to move the miner very much.  The module had to be installed at an angle for the header to fit.

I ran it this way for many weeks with the Golden 850 or whatever brand power supply, but I felt nervous about drawing 1030 W from the wall, and bought an OCZ ZX Series 1250W and installed it a few weeks ago.  This seemed to be a good power supply and is on the known good list on the avalon wiki.  I did (have to) remove 1 of the top plate mounting screws, as the power supply is a little taller than the original.

Today, I received the expansion module for a Batch #2 unit, and I did a swap out between the batch #3 and the batch #2 4th modules.  My Batch #2 unit is now an Avalon stock unit, with the replacement OCZ power supply and an Avalon (4th) expansion module.

I also have a 2nd machine.  It is a fire damaged Batch #3 unit.  I bought a controller, cables, PDU, and thermometers from bitmine.ch.  This is all Batch #2 compatible equipment.  The PDU is mounted on the original mounting holes.  The controller is freestanding.  The Golden 850 power supply from my Batch #2 is mounted inside the case.  I have a fire damaged module with 6 good sub-assemblies, and I am hosting another Batch #3 module for a 3rd party.  So, this Frankenstein unit is a mish-mash of Batch #2 & Batch #3, Avalon & 3rd party equipment.  It is currently mining at 256 MHz without the thermometers installed, and using an external fan.

What an adventure.