I have started to get inside the machine and a general layout diagram of where all the parts are inside is in progress. I've now have a rough diagram, but I'll be adding photos as soon as I can take 'em and get them scanned.
VME bus boards are all accessed via the rear of the unit, just below the 2 large fans that cool the 5.25 Full height HD Bays. Even the main CPU board is a VME bus board, and can occupy a slot anywhere in the unit. Once a card is slid into the unit, it connects with the backplane board, which connects the cards to each other. 6 Fans below the boards draw air down and out through the bottom of the unit (remember it's on wheels) and cool the boards and the power supply.
3/160
Processor(s): 68020 @ 16.67MHz, 68881, Sun-3 MMU, 8 hardware
contexts, 2 MIPS
CPU: 501-1074/1096/1163/1164/1208
Chassis type: deskside
Bus: VME, 12 slots
Memory: 16M physical (documented), 256M virtual, 270ns cycle
Notes: First 68020-based Sun machine. Uses the 3004
"Carrera" CPU, which is used in most other Sun
3/1xx models and the 3/75. Sun supplied 4M
memory expansion boards; third parties had up to
32M on one card. SCSI optional. One variant of
the memory card holds a 6U VME SCSI board; there
is also a SCSI board which sits in slot 7 of the
backplane and runs the SCSI bus out the back of
the backplane to the internal disk/tape (slot 6
in very early backplanes). CPU has two serial
ports, Ethernet, keyboard. Type 3 keyboard plugs
into the CPU; Sun-3 mouse plugs into the
keyboard. Upgradeable to a 3/260 by replacing
CPU and memory boards.