Here's my Chevelle for example. Note the wiring near the power steering/hydroboost hoses. If I need to pull the motor I can disconnect the senders and drape the harness over the fender and then reinstall in about 5 minutes.
It runs under the alt, over the water pump and the intake to all sensors:
Oil pressure, water temp, fan temp probe, choke, HEI, alternator, tach, etc.