The output resistance is quite low at dc and low frequencies. Approximately 0.1
ohms until the short circuit current limit kicks in above about 18mA. As the
frequency increases, the output resistance increases too as the open-loop gain
decreases. It’s about 150 ohms at 1MHz and it can be traced back 20dB/decade
from there, meaning 15 ohms at 100kHz, 1.5 ohms at 10kHz, and so on.