Note the 1971-1973 alternator mounting, on left side of engine, down low.

The original Nissan hoses have a braided covering.

The heater hose runs to the firewall, just to left of the rocker cover. At the mid-point, a clamp on the air cleaner bracket supports the hose.

You can use standard 1/2 inch heater hose (as seen here), though the original hose is of a thinner wall than usual, to pass more easily through the firewall grommet.

The small semi-clear tube running down the radiator is the original Nissan hose for radiator overflow. It connect to the port on the radiator cap flange and ends about an inch below the stone guard - it simply dumps overflow onto the ground. To improve this, add an overflow container like newer Datsuns have: when the engine cools down it will suck the coolant back into the radiator.