Main bearings??

[Dahoe]

hey guys some more questions regarding my 5.3. well i bought new pushrods and rollers for my hoe but it seemes to still be having the knocking noise "/ now my question is can it be the main bearings?? I did a test my proffesor told me might help me out on to knowing which one it might be. and well the knocking somehow stops but can he be right??? and is there any specs on how im supposed to remove them. i know each piston matches to its bottom end but is there like color codes to them???

 

[bkboatnsleds]

Normal GM Piston slap?

 

[Dahoe]

nope sounds worse than that, sometimes it does right when you start it and sometimes it doesnt. and today i took off the spark plug wire from cylinder #7 and it quiets down.