This has been a periodic obsession of mine. At my parents house, I have a Duo280c. I like the 68k macs a lot, and will be psyched when I get the Duo back to play with. The deal is that I really want to put together a powerbook with a FULL 68040 CPU, floating-point included. My Duo or a 540 would be ideal. I have a steady hand for soldering, and a bit of experience with reworking old PCBs (like the IDE controller on my Atari Falcon). I need to find 68k CPUs which I could drop in to such a laptop, so that the voltages and clocks are not problems. I guess these would be 3.3v versions.
Anyway, what kills me is that I KNOW there have been many devices over the years which have used these processors, and which I could now get for cheap. OTOH, I can still find new 040s, but at more than $100 each. I don't have hundreds of dollars to put into 040 chips which will be involved in a slightly risky surface-mount transplant! Anybody out there know of any computers, peripherals, upgrade cards, etc, which have the sort of 68040 I'd need for my PowerBook? I am amazed that it is so hard to find info about what kinds of 040 were built into what hardware.
Or, of course, info about anybody else's experiences with attempting this sort of thing would be exciting to read!