Some were compared in this thread. Don't ignore the upgraded model from Toyota (part no. 28800-21190) which showed in the comparison as a reasonable, competitive choice on both price and specs. -Chap
If you have ordered the Panasonic battery from a Toyota dealer parts dept (which Chap referred to in his post above), I hope that you also ordered the conversion kit which provides a new battery mounting bracket and terminal connectors. Otherwise, you will have to fabricate or procure those parts yourself.
If the battery you're taking out says Panasonic, the upgrade was already done and you don't need the kit. If the old one says GS, the kit would be a great investment. It's cheap, safe, and gives you a perfect fit. Between scrounged parts and your time to kludge something up, evaluate it for safety, etc., I'm not sure how you'll beat $31. The kit p/n was in the linked post, but it's 04003-23147 in case you missed it. -Chap
The main ECM operates from the 12v battery in the trunk. If the battery is not up to par the computer may cause weird things to happen.