Well I've got a 420 on my trailer so this thread may be very timely. But that's another story. I've looked over the front PTO and thinking something something different might work better. Army? You mentioned running a single belt. Have you done a lot of work with it that way? I'm thinking a single "B" belt may work just as well replacing the impossible to find dual clutch sheaves. Of course the PTO is burned up on the 420.