I bought this battery quite a long time ago and finally got a new T3 screwdriver recently. The battery fits fine. It's a little bigger than the old one and sits over the edge of the motherboard a bit, but it's wrapped in non-conductive plastic so that's ok. The hardest part was deciding how far to trim back the wires.
During this step I broke off one of the contacts for the charge connector on the side of the motherboard. I'm not sure if it still works.
I found a Motorola brand FX30 battery labeled as "new" on ebay for $30 from a seller with good reputation. Reading the amazon reviews for 3rd party batteries I saw a lot of comments complaining the battery isn't curved like the original and only sort of fits. The FX30 battery I bought is exactly like the one I took out and so is a perfect fit.
New Lithium Ion cells require 5 or 6 charge cycles to properly condition so I won't know if this truly is a good battery for a few days. But at least it fit like a glove!
A T2 and a T4 driver will both fit a T3 screw, but not as well. These are definitely T3 screws. They are not snug and no downward pressure should be needed if you use a driver that actually fits.
Here's an image with Screw #20 also circled: