Ask Superman. He might have something. It might help if you gave us a list and part number/NSN for the item. I assume, by air filter cover, you mean the Item number 42, of Figure number 8, page 0009-3. NSN: 2940-01-174-4181, Part Number: P11-9711.
The SMR Code in the parts manual tells me the possibilities of getting the cover alone, are slim and none, unless you go to the manufacture, or some kind hearted person will sell you just the cover. The cover's original cost was approx $22.00. The below listed companies provided air filter housings to the military.
| CNH AMERICA LLC | | | | | 700 STATE ST | | | RACINE | WI | 53404-3343 | | | |
| DONALDSON COMPANY INC. | DBA TORIT PRODUCTS | | | | 1400 W 94TH ST | | | MINNEAPOLIS | MN | 55431-2370 | | | |