Sorry, the piece you're looking for is not available separately. It is part of the Seat Belt which must be replaced in it's entirety.
You fail to mention either the model year of your car, or which side you're looking for, so here are the PN#s for each:
Seat Belt (Lt)
- 986.803.033.02 <'02
986.803.033.03 >'01
Seat Belt (Rt)
- 986.803.034.03 <'02
986.803.034.05 >'01
These are for the standard Black/Gray belts.
For colored Belts, change the last 2 digits to:
- .V02 - Speed Yellow
.H03 - Maritime Blue
.N13 - Guards Red