[tucsonjwt]

If you had not said you removed all of the belts, that would have been my first guess. Maybe you are looking too deep - could it be something like a pulley - crank or water pump? I had a bolt work loose on the crank pulley of my 454 and eventually all 3 bolts worked loose and the pulley eventually fell off - I have no idea what caused this, after 10 years of driving it and no engine work. The sound was a high pitched metallic "squeal", but not quite a a belt sound.