I know it's probably pointing out the obvious, but ...
the speedo cable's ticking sound will increase in frequency with the speed of the car. If you hear a ticking sound that is exactly related to vehicle speed, it's going to be the gearbox, transfer case, drive shafts, differentials, axles, cv joints, wheel bearings, brakes or wheels (even loose wheel nuts or stuff caught in tyres). It may also be road surface related, disappearing on different road surfaces. That points to suspension or loose parts (panels, cables, bolts etc).
If it's directly related to engine speed - which means, changing up a gear and the frequency drops - it's going to be gearbox (input side), clutch/flywheel or torque converter or engine.
In the engine, it could be bearings, valves, injectors, belts, alternator, water pump, power steering pump.
It might seem obvious to you but there may be readers out there that this helps with, and sometimes even a basic diagnostic like this is all that's needed to help pinpoint a problem.