| Factory | Number | Cross Interchange Type | Relevance |
|---|---|---|---|
| BENDIX | R521 | Direct Cross Interchange | 2 |
| FMSI | 2165T521 | Indirect Cross Interchange | 1 |
| CENTRIC | 11005210 | Indirect Cross Interchange | 1 |
| CARQUEST | RS521 | Indirect Cross Interchange | 1 |
| CARQUEST | GS521 | Indirect Cross Interchange | 1 |
| CARQUEST | BS521R | Indirect Cross Interchange | 1 |
| CARQUEST | BS521 | Indirect Cross Interchange | 1 |
| AUTOSPECIALTY | 3052103 | Indirect Cross Interchange | 1 |
| AUTOSPECIALTY | 3052101 | Indirect Cross Interchange | 1 |
| BENDIX | RS521 | Indirect Cross Interchange | 1 |
| A.B.S. | 40521 | Indirect Cross Interchange | 1 |
| MONROE | BX521 | Indirect Cross Interchange | 1 |
| HP | 1440 | Indirect Cross Interchange | 1 |
| RAYBESTOS | 521PG | Indirect Cross Interchange | 1 |
| RAYBESTOS | 521NR | Indirect Cross Interchange | 1 |
| WAGNER | PAB521R | Indirect Cross Interchange | 1 |
| WAGNER | PAB521 | Indirect Cross Interchange | 1 |
| MIDAS | BS1473 | Indirect Cross Interchange | 1 |
| SATISFIED BRAKE PRODUCTS | R521 | Indirect Cross Interchange | 1 |
| SATISFIED BRAKE PRODUCTS | B521 | Indirect Cross Interchange | 1 |
| OE | 12300218 | Indirect Cross Interchange | 1 |
| NAPA | AE521R | Indirect Cross Interchange | 1 |
| NAPA | AE518R | Indirect Cross Interchange | 1 |
| NAPA | AE507R | Indirect Cross Interchange | 1 |
| MIGHTY | 521EX | Indirect Cross Interchange | 1 |
| FMSI | 521 | Indirect Cross Interchange | 1 |
| FMSI | 2165T521amp160 | Indirect Cross Interchange | 1 |