I was at Sears yesterday and the guy showed me the Group 35 size and it did have the same or slightly smaller measurements than the Trustart.
The sears guy said it had 740 CCA and 100 mins. reserve capacity. These numbers are often meaning less unless they tell you at what temperature the numbers are valid.
I have also read that when an Odyssey goes out it does not fail catastrophically although I don't know it that's true.
What I like about the Odyssey is I've used them sports cars and track cars and they don't leak, so if you don't have a battery tray it's no big deal. My brother uses them in smaller aircraft and they do give specifications at different temperatures.