Which Damper mdid you get? What type of Timing cover do you have? When I had my Indy Cover on my Engine I ordered the wrong damper and a call to ATI got me a replacement which let my pullys line up without any crazy shims or spacers...just saying...

They have four or five different length Mopar hubs.

http://www.atiracing.com/products/dampers/charts/damchrysler.htm

Hope this helps or it's cutting time!