A "limitied slip" type of posi like the Ford Traction lock is the best set-up for the street . it allows a limited amount of slip to occur when cornering. hence the name. a full posi like you mentioned means a spool type to me. where both rear wheels are locked together at all times. very harsh on the drive train. U-turns and parrallel parking can be a chore. but they are stronger than limited slip posis'