Look by the balancer.
No crank sensor, only the sensor in the distributor.
inside the distributor
the o2 sensor is located on the exaust manifold
Driver side of the bell housing.
There is a crankshaft position sensor that measures how fast it rotates
Behind the harmonic balancer (dampner) that is located behind the crankshaft pulley.
If your looking for the oil level sensor it would be located on the driver side on the oil pan.
paste this into your browser...i could not get the link box to take.. but this should ansewr the question on the o2 sensor
I don't know if it is the same as the Ford Mustang , but the BAP sensor was mounted on the firewall - good luck
In the distributor.
motorcraft . com just shows ( 1 ) oxygen sensor for all available engines in a 1991 Ford Ranger
The sensor is located at the lower center of the engine block back side. Has a plug with two wires that attaches to the sensor. One 8mm bolt holding the sensor on place. You will have to be under the vehicle to see the sensor location on the rear of the engine.