I've got a 97 truck, broke the crank, swapped in a motor from an 07. Heads down is 07, intake up is 97. had heads planed and a valve job with new seals done. Left it alone from the rings down. Got it in this weekend, running today. Ran it in the driveway with no load for about 30 minutes, top end was noisy for about 5 minutes till the top end got good and oily (I'm assuming). Purred like a kitten, sounded real smooth. Took it for a drive around the block, heard the clatter in the video below. It's almost always there when driving. Brought it back, turned it off to check oil, it was a quart low. Added oil, startup was VERY labored with a real hard knock in the bottom end. Ran like poo till I gave it some throttle for a couple seconds, then it cleaned up and idled well. Let it run for a couple minutes, turned off and let it sit for a couple minutes then started back up, same thing. Very labored with hard knocking. Can anyone tell me what this is?