Hmmm, MSD's website clearly states that it will not work with the 6.1L, don't understand why as the both have same wheels.
Simplest thing to do is return the MSD and call FAST they have a similar product at a similar price that will work with the 6.1.
http://www.compperformancegroupstor...re_Code=FS&Product_Code=301314&Category_Code=
Shop around, a lot of resellers sell it cheaper than the FAST website.
Regards,
Joe Dokes