Since I put the '04 6.0 in my '00 Silverado I've been having some trouble keeping the drive pully for the whipple on right. I finally called whipple tech support and found the answer I expected.

Whipple quit making the two belt system in late '01. Since then GM changed the harmonic balancer. Now my whipple pulley doesn't sit flush against the front of the harmonic balancer, but is sort of cradled in the valley there.

There is a really cool guy at whipple who faxed me the specs on how to machine my pulley to fit the new harmonic balancer since he couldn't sell me the correct one.

He also told me they are going to have the ability to retro fit the old compressor onto the new snout so you can run a single belt set up. This will do two things for everybody with that old 2 belt whipple setup like me.

1. Easier access to the discharge side of the whipple so you can fit an elbow in there for intercooler piping.
2. It will increase the diameter of the drive pulley from 6.25inches to 7.5inches. Making more boost with less belt slip.

I'm supposed to get a price quote on the conversion in the next couple of days and will keep everyone updated.

In the meantime...I guess I have to get a pulley machined if you know anyone in the Austin area who can do it I would appreciate the name.