Hi Bill,
I'm not seeing a Vendor Part Number in Dynamics 365 for Financials, are you referring to Cross Reference Numbers? Just want to make sure I'm looking at the right thing, please let us know if you are looking at something different.
Right now the Cross Reference Numbers are not able to be printed on PO's but this has been communicated to Development and it's something we are working on getting added.
We had a very similar question raised in this Forum post: community.dynamics.com/.../221746
Regards,
Jennifer Reinhardt
Please see our Dynamics 365 Financials Support Team Blog for helpful information:
blogs.msdn.microsoft.com/dyn365finsupport