when I try to put transmisson in park it grins and have to turn engine off to pu on 2000 Volvo C70

than the car still rolls

Asked by for the 2000 Volvo C70
Check the shift cable, sometimes the "eye" bushing at the transmission will wear or break causing a loose connection. If so the trans will not lock into park position, If that is in good condition the parking paw in the trans may be bad where it won't be able to lock.