my 97 cobra had a rpm depended knock ..which sounded like rod knock to me, after i dropped the motor i check all of my rod bearings i didn't find any spun bearings. then i checked my mains the only thing i found was the thrust bearing and washer where about .02 off and where hitting the crank . side note ,before i unbolted any thing i noticed there was to much slop on the crank it move front to back to much . my question is what would case this and will it happen again , iv never ran in to this . i have a new crank in it and its real tight.