Your 01 Ranger expects the speed signal to come from the PCM which processes a signal from one of the internal transmission sensors.
The 99 Expo gets its speed signal from the ABS system.
So, with the 99 Expo 5.0 in your 01 Ranger, you'll be without a speed signal.
Think you've got two options, maybe only one.
If possible, you might be able to add in an earlier VSS, it's a mechanically driven signal generator from the old school speedometer drive gear at the output shaft of the transmission.
Other option is to graft in parts of the Expo's ABS and Inertia/G-force sensor.
PATS -- easiest answer is to graft in the Expo's PATS module and transceiver. ZIP tie the Expo key into the transceiver and simply bypass the Ranger's PATS transceiver in the steering column altogether.
Strada Shop over at Ranger Power Sports was sill selling the adapter plates, or I've got some dimensions for a flat set of flat plates. The flat plates will raise the engine up about 3/8" from the Stada Shop ones but that will only add clearance at the rack and pinion unit.
Some great guides:
Everything you wanted to know about PATS - Ford Explorer and Ranger Forums "Serious Explorations"®
Swapping An Explorer 5.0L In To A 1998-Up Ranger
2001 Ranger 5.0l Swap Wiring Guide!!!!