FYI, here's the "tank farm" that is spoken of:
Duo 230 (68030) foreground, 2300 background (PPC 603e). Also FYI, the 230 display connection will not hookup to the 2300 motherboard without some sort of adaptor. The 2300 display port is closer to the back of the unit (ie, away from an imaginary user) and is larger. Since the 2300 board was offered as an upgrade option, I imagine there was an adaptor ribbon of some kind. You can see the 2300 display connector in the hole to the modem-side of the CPU, the whitish vertical up pointed port. The 230's is right behind the large chip just to the modem-card-side of the CPU, and is a black connector that is perpendicular to the general orientation of the board (as where it is now, it's right near the reset button on the 2300's board.)
EDIT: I'm thinking I might do a write up on the Duo boards. They might be all identical, I mean there's just the 68030, 68040, 68LC40, and 603e, there can't be that much difference in the capacitors we are after. They do look big, juicy and could let off quite a BANG if they wanted to.
EDIT 2: I have the 230 board right in front of me here, there are:
2x 100µF 25V
1x 330µF 16V
3x 100µF 35V
1x "W1 33 25V" with a line over the W. Probably 33µF at 25V.
Not too bad. Soldering in the proper order (ie this one first, then this one, then that one) is probably advised, lest you box yourself in
As for the 2300 and the others, well, I'd have to ask our fellow soldiers for that, since I don't have a 210, 250, 270 or 280. As for my 2300, well, I'd have to take my 2300TB apart all over again, removing the CPU stiffener isn't exactly fun...but not as bad as the iBook G3 600MHz on up...