I am assuming the tacho head unit will be the receiving end for the plugs to er plug into.
I am guessing they are not std landrover plugs/loom, so you will need to trace them to see what goes where.
As the car is quite old it might have had an analogue tacho which are the type that take paper discs, which are real old school stuff.
this is info for a digi tacho 2008 onwards.
LAND ROVER DEFENDER TACHOGRAPH FITTING INSTRUCTIONS AND INSTALLATION
vdotachograph.co.uk
The wires could of course also be for some fancy radio gear, but it does seem like a lot of plugs for that.