The Del Vikings were one of the first rhythm and blues groups to take elements of rock and roll and introduce it to the musical format of doo-wop.  They successfully blended the rock and roll sound into doo-wop without destroying the rhythm and blues sould of doo-wop.  This is evident on many of their records like Come Go With Me and Whispering Bells and why they are considered to be real ground breakers in the world of group harmony.  It probably also explains their wide-ranging appeal both in the original days of doo-wop and now.