#1 rule - do not tell your local Kubota dealer you have a grey market tractor, that may cause issues with your relationship and they may refuse to help you with parts.
I have a cozy relationship with my dealer. They ask for a serial number almost every time. I have found out over time that my B6001 is mostly B6100 and smattering of B6000 parts for good measure. I got a legit North American serial number for both and depending on the part I need I give them that. Keeps both of us very happy. The dealership thinks I have two small tractors.
The good news is that with this forum, the parts and service manuals available to you on similar NA models I have been able to source the majority of parts locally.