I think you're looking at it right. From what I have found, the first 5 digits are like a group # for a part category, then the last 4 spell out the exact part.
Differing part #'s may not mean that they won't work, it just may be different becase the factory made a slight change such as changing the casting slightly to loose weight or gain strength. Different, yes. Bolt on and work perfectly, maybe.
The reason that I use the aftermarket as a starting point is that those companies do thier homework very well before they put a part on the market. They don't want anyone bitching and moaning about a part that didn't fit thier bike.
torch