so your problem is a missing wiring diagram for the speedo
- any chance of
1: link to the item you bought (just so we can see what is there)
2: a list of wires you have i.e black,blue, blue (Red tracer) ETC ETC
we might be able to help you out with wiring decoding
if there is a black wire with a white tracer that is prob your earth add that to negative on a battery and test other wires on positive to see what lights up