The crank will physically fit..yes...however you'll crash valves without a reduction in valve lift. The Tone Rings have been changed...yes they are interchangeable...make sure you change your crank sensor too if you do that.

Originally Posted by mattw
Will a 6.4 production crankshaft fit in a 5.7 6.1 2003-2008 hemi?
I know the crankshaft toner ring has been changed since 2009.
Will the toner rings from earlier hemi bolt on a production 6.4 crankshaft?
Matt
I posted this to a bunch of SRT engineers and their response was written on top.
Thanks to Steff i found out that the production 6.4 crankshaft has to be machined on the snout to make the early 5.7 6.1 hemi timing chain work. Plus on top of that, found out the toner rings are 3 bolt (early), 4 bolt late model.
How the hell does that make them interchangable.