http://www.oxygensensorwholesale.com/ford_1990_mustang_lx.html
1990 Ford Mustang GT/ LX Oxygen Sensor
Engine: 5.0L GAS
Year: 1990
Brand: Bosch
$38.80

http://www.maximumautoparts.com/FO_Oxygen~Sensor_MUST-GT-002_items.html
Ford Oxygen Sensor
Brand: Bosch
Year Range: 1984-1995
Fits: 1985 to 1985
Category: Ford Fuel Injection
Model Engine: V8 5.0
Make: Ford
Model: Mustang GT
Price: $37.20