Nissan Largo 2.4 petrol auto 1996

[vectra5d]

Hi,
I'm Allison,
I recently bought a 1996 Nissan Largo 2.4 petrol 1996 to use as a day van.
I have insured it on limited mileage, but unfortunately the speedo doesn't work...
I have had it checked out, and it appears the sensor in the gearbox is faulty. Does anyone know where I can get one from?
I really like my Largo, but it does concern me how difficult it is to obtain parts.