I was looking for an auto-battery replacement of my Sienna XLE 2005 at Costco. When I asked the salesperson, he pointed me to a Costco battery for about $70 + tax (and there is no charge for returning the old one to them). It's number 3 and the group size is 35, but when I tried to install it, it wouldn't fit as the size was smaller and the anode (positive terminal) and the cathode (negative terminal) were at the opposite side, unlike the original one,. I went back to Costco to exchange, but unfortunately they didn' carry the one I wanted (interestingly, the reference book they had really showed group size 35 was indeed the only group size for my car, not group size 24 as written on the original battery).
I ended up returning the battery and went to Kragen. Luckily, they have this type, as well as the 35 (strangely, their computer initially showed group size 35 as well, but the salesperson said they carried also the group size 24). It costed me about $80 with 84 months limited warranty (but 36 months full warranty).
Went back home in rush to install the battery, and now it works flawlessly, at least for now.