Someone posted this link a few days ago on Treo replacement batteris. Since the search on Treocentral wasn't working I coudn't locate that thread so I'm starting a new one.

Per, the Treo 300/270 uses a 850 mah battery, whereas the 180/ 90 uses a 1000 mah. They look very similar in size. I called and requested a dimension of both batteries but it was not available. I've asked them to measure it and they said to call back later. Anyway 150 mah extra is about 17% and that is another 35 minutes of talk time. Do you think this is worth pursueing?

I took apart my Treo 300 last night and can confirm that it has a 850 mah battery. It was fairly straight forward to disassemble. I also took about 8 detailed 1600 x 1200 jpgs of the guts of the various assemblies inside, including the main bd, the LCD module, the key pad, the back cover, the antenna. If you have a site that can host the jpgs please contact me. I can e-mail them to you so all on Treocentral can see.