So firstly, from a drawing point of view you don't have to assign them your own unique part number. Use a vendor/manufacturer part number, using an MS or similar might be even better. For instance, you could use something like the McMaster Carr part number or a similar catalogue. You could qualify this with an 'or equivalent' statement, though there may be some risk.
It's surprising how many descriptions used are actually incomplete or open to misinterpretation. Referring to a specific vendor/manufacturer & part number significantly reduces this likelihood.
We're actually gradually updating a lot of our assy drawings to add more 'manufacturer part numbers' for even fairly standard fasteners, since descriptions alone are sometimes unclear to our offshore vendors.
We don't typically create a BOM in SAP for our inseparable assemblies, we treat them as we would simple parts. However, the drawings have a parts list with the pem studs or whatever as well as the basic sheet metal or machined part. Due to limitations of our SAP implementation, our CAD package and our established doc control system, we fudge a few aspects but it seems to work.
When outsourcing (be it domestic or foreign) it’s even more important that the drawing is unambiguous and easily understood, following established standards really helps with this.
I’ve never seen a really good Japanese drawing, they’ve always been a bit lacking. Now clearly this hasn’t held them back much, but unless you’re also copying whatever else they do that makes it work for them, I’d be careful.
Also, I learnt, and occasionally have to relearn, just because I’ve done something a certain way before and apparently got away with it, doesn’t necessarily mean it was the right way.
MadMango, if the OP is creating the fully detailed drawings, and just outsourcing the actual manufacture, then a Source Control probably isn't appropriate. We outsource most of the inseparable assy type work and some assembly work, we experimented with expanded use of Source Control drawings but it didn’t' work out. Conventional assy drawings do seem to work, you just need to make sure all items are adequately identified that anyone can go buy them without access to your ERP system.
Posting guidelines faq731-376 (probably not aimed specifically at you)
What is Engineering anyway: faq1088-1484