Over the years, Nissan changed the rated HP without doing any changes to the engine itself. Sometimes going up, or going down. This goes even further into the P40 engine, basically a small redesign of the P engine, with it's core components remaining the same: displacement, compression ratio, camshaft. My guess is that "lawyers" got involved
The following data is taken from various brochures, leaflets, including some from Australia. There's no consistency. I will stick with my 65 ID Plate, of 145 HP
1963 ID Plate
HP: 135 @ 3400 rpm
1965, 1968 (also a 1969 Owners Manual)
HP: 145 @ 3800 rpm
Max. Torque: 235 ft-lb @ 2000 [32.5 m-kg]
1975
HP: 130 @ 3600 rpm
Max. Torque: 217 ft-lb @ 1600 [30 m-kg]
1977 Leaflet
HP: 145 @ 3800 rpm
Max. Torque: 235 ft-lb @ 2000 [32.5 m-kg]
1980 P40 engine
HP: 135 @ 3600 rpm
Max. Torque: 217 ft-lb @ 2000 [30 m-kg]





