There are many that will work. I always used the 66 belt and had no issues. The 42,70,1105,ect. are all std. belts with no ribs on the backside, I was told for extra cooling.? The ULTRA is definetly a High Perf. machine, so the 66, or if you have a need for harder rubber compound, the 67 would be needed. If you dont terrorize on your ride a 1105 or the 42 belt may work fine. Also they make good ride home belts(less expensive) if you tear one up.
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