Ok, good. This means that you shouldn't throw a code 24 at the wrong time when the ECM "thinks" you're in Park or Neutral and driving down the road. Otherwise, the ECM could care less what other gear you're in.
Clear all your codes before doing anything related to the VSS. A code 24 that sets when you're not moving doesn't count. Most of the time when a speedo cable breaks or comes loose and you're driving around is when you usually get a 24 code.
Speedometer working ok.
Lift drive wheels and support rear axle so the car can spin the wheels without going anywhere. SAFETY FIRST. Be extra careful if you do this in your garage or close to other objects/cars.
Backprobe CKT 437 and be ready to check for voltage to ground
Start car, let idle, and place in drive. Voltage should vary from 1 to 6 volts.
If it's <1 Volt, there's a short or poor connection at the ECM. If it's 8-12 volts and steady, you have an open somewhere in CKT 437. If it's not shorted or open, it's likely a faulty VSS. If it is 1-6 volts, everything is working as expected.