After exhaustive searching I’ve found these numbers for North American spec cars produced.
1985: 1,847
1986: 1,759
I also found this for official sales data which doesn’t list the model year only how many were sold each month. The total for 524td’s comes to 3,635 units which leaves us with a 29 car discrepancy. I own a US Spec 1984 MY 524td’s. This data suggests there may be 28 more ‘84’s, or possibly some ‘87 MY cars. Does anyone else have an 84 or 87 North American Spec car?