I put a Powerbond dampener on my 540 but wish I had used an ATI. The reason is the PB is thinner and the pulleys needed spacers to match what I had on the previous install with a different motor that had an ATI. It also interfered with the cast Indy front cover but I may have the wrong version of that and it was fixed easily enough with a milling machine.

The PB has that huge snap ring in front which I think makes them easier to rebuild. But sending the other dampener to ATI with $75 also gets that done. We'll see how it does as the 540 is very close to first fire after severely hammering on the Proparts (TTI) 2 1/8 step headers to get them to fit in the car.