I've got the Fiat twin cam 4/4 and I think I know what you are refering to. Is it on the underside where the Bell Housing meets the Sump Pan ?.If it is then there should be a bent metal cover held on with four M6 bolts covering that area Flywheel Inpection Plate

Owen
"bilibib"
1982 4/4 Twin Cam, Royal Ivory
1932 Super Sports, Duo tone(two tone)Green