I bought some Mk1 door hinges at the weekend, sold on the premise that they were a full set as I know all four hinges are different. I'm pretty sure I've worked out that isn't the case, but thankfully I'll only need to source one new hinge as three of the hinges were from the same car. What I want to know is how to identify where the hinges should go (i.e. drivers top, passenger bottom, etc.).
One of the hinges is brass, and has a raised 21 on the inside:

The other three are rusty steel hinges, with the numbers 3, 4, and 6 indented in to them:



So then, where do they all go?
21 (brass):?
3 (steel):?
4 (steel):?
6 (steel):?
Any help would be great!
Cheers, Sven.