The 4R01 was a 4-speed automatic transmission from Nissan's Jatco subsidiary for rear wheel drive vehicles with longitudinal engines.
The RL4R01A is a hydraulic controlled unit for its main operation.
Shift timing is based on throttle cable position and governor pressure.
Its only electronic parts are two solenoids, one for the torque converter clutch, and the other for the manual overdrive cancel switch, but these do not affect the gears control and passing.
Despite the internals are mostly the same, valve bodies, cases and housings have some divergences with the RL4R01A.