Vortec 5.7 Mystery Sound

[dmulally]

Hi All,

I just installed a 350 Vortec from a '99 pickup into my 66 C20 that has a 700r4. On first start up I heard this god awful noise and could see some deflection from the front pulley so ordered a new one and replaced it. The sound persists.

To me it sounds too fast to be a stuck lifter. I took the belt off and the sound remains as I thought it sounded fast enough to be the water pump impellor.

My problem is that I'm mostly deaf so I can't actually tell which part of the drivetrain it is coming from. Flexplate bolts fouling to front timing chain I have no idea. Would anybody be able to have a guess as to what it is?

https://youtu.be/4jvq_UoU3M4

Thanks in advance.