NOT an automatic, Fluid Drive semi automatic. You do need the clutch to shift from forward to reverse and back and to shift back and forth between high and low ranges.
You're right about the transmission. This a modern version of the fluid drive. Both this and the older fluid drives were 4--speed To start out, use Low(L) on the shift indicator. This would be first gear. With the car moving slowly, release the accelerator briefly then step on it again. A big clunk is heard, and the car has shifted into second gear. To go to third, depress clutch pedal and move the shifter to Drive(D). To go into fourth gear, release the accelerator briefly, hearing the big clunk. Now in fourth gear. The fluid drives are semi-automatics, as the driver has to do some shifting. Note also in 1953 the DeSoto was available with three-on-the-tree manual.
@@rayfridley6649 I heard that a lot of people just used the high range when driving. Would have made for slow acceleration from a stop but almost no clutch pedal use.