Crankshaft/oil pump seal

Hi, i have purchased two crankshaft seals timing end for my vectra but both are slightly too small,they will start to roll back with spring departing from the seal.These are quality seals Elring Payen etc,of correct dimensions and assured correct replacement parts.With research i have found GM seal 90501720 ,may be a slight difference to patterned parts.Engine is X20XEV.Any one else had this problem?