help with speedo

[butty84]

i've got a 1972 bay with no speedo in it so took the speedo out of my 1975 bay to see if it would fit. before doing this i made a note of where the wires were and what colour etc. when i tried to wire it up there were more wires than on the newer bay, some of which were new spade fittings, do you reckon the previous owner had extra gauges or is it a different beast all together?? would an auto electrician be able to fathom it??