Here are your parts.

Sounds like you have replaced or greased most things that are involved with the drum rotation.
Grease is not a great idea in a dryer as it will collect and hold lint but it should have either eliminated or reduced the screech if you had found the correct part.

I would open it up and check for any signs of wear on the drum at the back and the front.

Spin the motor to see if it is OK. It is possible that it's bearings are shot also could be that there is something in the blower scraping as it rotates.
Sometimes the motor bearings will only make a racket when there is tension on them from the belt.

I would also check the endbells on the motor, see below.
http://www.applianceaid.com/drymotor_bad.html