When looking at even new factory dampeners, it appears there is a crack across them. I believe it's a production mark or something.
The double roller is made for the AUS motor and needs to be corrected to fit our motors. The specifics are the chamfer/nose of the crankshaft is different.
Holler if you need an intermediary to get the PBM's. There are a lot of folks here as well that say keep stock springs on rockers. Then there is the other side that says, if you start spinning the motor faster etc..you can have some float. I believe potential float is why most change springs. I've always felt that if you changed the valvetrain, you should change springs to compensate...however many do it w/o issues.
