After deciding the battery in my 03 was not going to make it through the winter. Among other things it couldn't even light up its indicator after a lengthy daytime drive. So I decided to do a bit of shopping. Thought I'd pass on the results.
The stock battery is a 690 cca ACDelco in a fairly new group size: 101. Not many places carry a group 101 battery, and those I found were pretty pricey. Now, it turns out that a group 101 is almost exactly the same width and length as a group 78 battery, and about a half-inch shorter. In the cts, incidentally, it sits on a battery tray that's at least that thick.
Solution: Wal-Mart MAXX group 78N. 900 cca. Warranted free replacement for 3 years, prorated replacement for years 4-9. Top of the group 78 ratings at Consumer Reports, and a best buy. Paid all of $68 + tax.
It's a tighter fit than the original, but not so tight as to require bending, cutting or hammering. I though I might have to 'adjust' the thickness of the battery tray, but doing so was not required.thanks plugh