Hello mate,
You'll find the chassis number stamped on the front off side of your chassis,
Locate the four bolts that bolt the power steering box onto the chassis and in the middle of the bolt heads you'll find the chassis number, you might have to scrape off years of grit & grime but that is where you'll find it.
It should also be on the VIN plate on the front panel underneath the bonnet on that age RRC.
Cheers,
Ron.