Do you have an optima? Mine seemed to fit in my battery area, of course the hold down probably wouldn't work, although I never tried. The only thing about mine was that it's shorter than the stock battery area and so it would slide down and pinch my overflow hose, but I threw a piece of wood in there to hold it back and it's fine.
Part Number: Red34/78
Model Number: 9083547
Cranking Amps: 980
Cold Cranking Amps: 800
RC (no idea what this is): 104...maybe recharge rate?
Price: ~$120 at pepboys