More info: A quick google turned up this. Crazy detailed with some compatibility charts linked. It looks like the most common problem you might run into when swapping manufactures is if your device *requires* a 128 cycle refresh; 256 cycle chips won't work. (The reverse should be okay, however.) If there's any question and you don't have sufficiently detailed service documentation/schematics with the information Googling for the datasheet of the chips you're replacing should tell you whether a 256 cycle version will work or not.
There are one or two really oddball devices, like a couple Motorola versions that offer a built-in refresh counter triggered by pin #1, but it's not likely anything Apple uses them.
(The modifications to the PET I have were done by the guy I originally got it for and later decided he didn't have room in his life for it, and are beautifully done. Since the +12/-5v regulators on the Dynamic Board PETs aren't used for anything else he desoldered them, insulated their pins with shrink tubing, and glued them back to the board. The rest of the mod is two *very well hidden* jumper wires so it looks stock, only looking at the chip labels gives it away. But, again, a Dynamic PET motherboard is much, much cheaper than an Apple ][ board these days.
Also, weird triva: The chips that were replaced were actually "4108s", a *really* oddball device that electrically is the same as a 4116 but ignores A13, thereby only providing 8k of RAM. Rumor has it that these are actually 4116 dies with one bank disabled, either because it was bad or just completely for marketing purposes. I don't think anyone used them but Commodore, and Commodore was somewhat infamous when it came to intentionally crippling things in order to upsell the consumer. All common versions of the PET all the way back to the static RAM versions had two memory banks, and when Commodore discovered that customers were buying the lower memory models and soldering in the sockets to populate the second bank themselves they started literally sawing that part of the motherboard out on the cheaper models.)
There are one or two really oddball devices, like a couple Motorola versions that offer a built-in refresh counter triggered by pin #1, but it's not likely anything Apple uses them.
I don't know offhand, but I wonder if the later "platinum" IIes also use 4(1)464s. I also think there's a really-low-chip-count version of the "enhanced 80 column" card that must use them.
The mod is mentioned on that C64 wiki page, but: here's a link discussing how to make an adapter for replacing a single chip (You can also do this by just bending up the affected pins so they don't go into the socket and soldering appropriate jumpers to them), while here's an example of modifying a device motherboard to replace a whole bank. Should probably stress that you likely *don't* want to do the latter to something that might have collector value, like an original Apple II board.
(The modifications to the PET I have were done by the guy I originally got it for and later decided he didn't have room in his life for it, and are beautifully done. Since the +12/-5v regulators on the Dynamic Board PETs aren't used for anything else he desoldered them, insulated their pins with shrink tubing, and glued them back to the board. The rest of the mod is two *very well hidden* jumper wires so it looks stock, only looking at the chip labels gives it away. But, again, a Dynamic PET motherboard is much, much cheaper than an Apple ][ board these days.
Also, weird triva: The chips that were replaced were actually "4108s", a *really* oddball device that electrically is the same as a 4116 but ignores A13, thereby only providing 8k of RAM. Rumor has it that these are actually 4116 dies with one bank disabled, either because it was bad or just completely for marketing purposes. I don't think anyone used them but Commodore, and Commodore was somewhat infamous when it came to intentionally crippling things in order to upsell the consumer. All common versions of the PET all the way back to the static RAM versions had two memory banks, and when Commodore discovered that customers were buying the lower memory models and soldering in the sockets to populate the second bank themselves they started literally sawing that part of the motherboard out on the cheaper models.)