Explorers all used 4 wheel ABS
The speed signal for the speedometer(All Fords use 8,000PPM) came from the 4WABS module in 1996-2001 Explorers
In Ranger's the speedometer signal came from the GEM module, 1998-2000
BOTH Explorer and Ranger used the rear axle ABS VSS sensor as the source, but different wiring pathways and converters in those years
Rear axle VSS sends about a 25,000PPM signal, so can't be used directly for speedometer
Not sure if the Ranger 4WABS module was ever used for the conversion in these years???
That's the missing piece in your conversion, Explorer 4WABS module
2001-2011 Rangers used an OSS sensor on trans or transfer case to the PCM(computer), PCM converted OSS signal to Speedo signal, and sent it out to cluster and cruise
You lose this signal when you swap in the Explorer V8 computer
1995-1997 Rangers still had the gear driven speedo setup on trans or transfer case, no cable just the VSS was hooked up, and it was set for 8,000PPM(pulse per mile) by adjusting tooth count of the driven gear
So if you put in an older transfer case(1997 and older) with the speedo gear setup you can use that directly to the speedometer
Depends on the year of the Ranger as to how you would wire in the speedometer signal
If its a 2001 or up Ranger easiest thing would be to use a Dakota Digital SGI-5E interface hooked to rear axle VSS, also good for changing tires sizes as re-calibration is easier
I think all the Ranger 2WD automatics have the speedometer worm gear machined into their tail shafts, 1985 to 2011(A4LD to 5R55E)
So if you get an older tail shaft housing with the hole for the speedometer gear setup you could use that for speedometer signal, i.e. driven gear with VSS