If you need a new harmonic balancer Id look into steed udp. As it replaces the whole thing and depending on how much it's going to cost to replace it and also buy the BBK underdrive pulleys it might be in the same price range at the end.
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Oxford White Roush Stage 1 SN# 6925--SOLD but never forgotten!
Kona Blue GT premium - Slammed on BC's and BMR's full rear suspension