Bronco II's all use speedometer cables, if there is a VSS then it was used for cruise or computer, not speedometer
You will need to pull the Speedometer Driven gear out of transfer case and have a look at it
One bolt and you can pull out the speedo cable and with its Driven Gear
Looks like this:
https://www.therangerstation.com/tech_library/images/speed/speedocable_withgear.JPG
If it also has a VSS then it will look like this:
https://www.therangerstation.com/tech_library/images/speed/vss_withgear.JPG
The speedometer cable runs the speedometer either way
You can take an electric drill and spin the speedometer cable while its off, that will tell you if cable may be the issue, or speedometer itself
Use reverse-able drill, can't remember which way it spins, but won't hurt it to spin it backwards, thats what you do every time you back up, but no speed will show
Could just be burned out bulbs in the dash
Check speedometer first
Then if you have to pull the cluster you can check the bulbs