I see these boring heads come up for sale occasionally, usually brutally expensive if they are in nice shape. Unfortunately, they typically have an arbor like MT# or Cat# that is different than my (R8) mill spindle. I was wondering if any of you know if/how the arbor can be removed & replaced with an R8? Specifically I would be looking at one of the smaller units UPA 1,2 or 3. I downloaded a set of operating instructions, but they don't really show the arbor as a removable part of the assembly like other boring heads.