Battery sizes, testing amperages, and sifficent amps question

[darkone]

hey all, some guy has a Power 65 battery on CL and says it was tested at 530 cold cranking amps.... mfg's in nov '07. now ive been reading a bit about batterys and from what i understand the 75 is actually what GM cars should have as far as size, but, the truck im driving actually had a 65 in it when i bought it, but i wanted to know what you guys thought on the whole battery scenario. i want to have something that will not sputter out trying to start mah truck, ya herd? =) thanks for any info/ideas all!