How is this 1950's DC blower motor with 2 black wires and 2 red wires supposed to be wired?

Question

My brother bought an old Flxible Visicoach and it came with this DC blower motor for the heater:

I've searched (appears to be a GE 5BN56LA15) but can't find a mention of it anywhere. I've torn it apart and cleaned it and it seems to be in really good shape, I'm pretty sure we could wire it up and make it work (there's also 1.5 ohm rheostat with massive ceramic heatsink for controlling the fan speed).

But I wanted some feedback about exactly how it's supposed to be driven. When the heater is on, the rheostat connects the "BAT" terminal to the "FIELD" terminal. The other side of the rheostat is labeled "ARM"ature. So the field is always energized and the speed is controlled by varying the armature voltage. Simple enough.

The concern is the motor has 4 wires - 2 black and 2 red, as below.

Is it as simple as tying the black and red on the left side of the schematic to GND, the remaining black wire to "Field" and the remaining red to ARMature? (And swapping a red or black pair if needed to get the correct direction.) The colors make that solution feel a little uncomfortable...

Anyway, that would be my guess, but then I saw fancy wiring options like these:

And I wonder if there might be a reason it has 4 wires instead of 2.

Update: Here's the fan speed control by request:

Answer 1

it says that it's shunt wound, so it's pattern (b) above,

The motor will spin in a different direction depending on which way you pair the black and red wires; so 4 wires gives you the option to reverse the motor.