Aside from what others have mentioned, PowerBook A1138 and A1139 models were not sold for very long, and both were only offered several months after the switch to Intel was announced in June 2005. To the average consumer in late ’05, the DLSDs and the SLSDs appeared to be basically the same 1.67GHz model, but the former was being sold for about $200 less (and with a higher-res LCD). That was it. A lot of pro consumers back then opted on a wait-and-see approach for the upcoming Intel MacBook Pros.
As for the PowerBook A1025 (the 867MHz and 1.0GHz models), two considerations reflect probable lower production numbers.
One was overall
build quality, fit, and finish of the Titanium series, whose
flimsy, fragile hinges were already a known problem by the time of the November 2002 A1025 867MHz/1.0GHz release. By 2005, hinges were no longer available from Apple as OEM replacement parts, with working hinges from donor PowerBooks going for as high as $250,
each, on eBay at the time (with third-party hinges, plus servicing,
increasing that to $350). In fact, the 400MHz Ti PB I acquired in a trade in August 2005 was a recent recipient of a donor-sourced hinge, and by then, other components of that particular Titanium-series design, like plastic cracks, made it necessary to relegate it to basically a compact desktop server.)
By late 2002, plastic fixtures, like the top case frame, were already
known to crack easily and discolour quickly. The novelty of the Titanium design, by late 2002, especially considering then-known costs and upkeep issues, was nowhere what it was in January 2001 (when that form factor was débuted). Moreover, the A1025s still relied on PC-133 memory, all of which were already on the way out (and something consumers at the time regarded as a near-term dead-end, with no path to upgrading beyond 1GB) at a time when much faster PC-2700 SO-DIMMs had become the new standard for new laptops.
Two was how, barely 60 days after the A1025s went on sale, the aluminium 12" and 17" models débuted, leaving consumers who regarded the 15" form factor to be their “goldilocks” ideal, to either try out these new models or wait a few months longer for a 15" aluminium model to premiere. For those final eight-and-a-half months, the Titanium 867MHz/1GHz models were fragile units lacking Bluetooth, Airport Extreme, and much in the way of forward-compatibility, and people shopping around knew to probably wait until the next 15" refresh.
I hope this clears up any residual confusion you’ve had about that series of PowerBooks.
