I have a 1963 Rambler American 2dr Station Wagon flathead 6cyl. automatic trans. At the end of the driveshaft that fastens to the differential (pinion portion) there is a large nut that is about midway between the yolk on the driveshaft and the front face of the differential. Is there supposed to be such a gap where this nut is sitting? This large nut has a flange looking piece to the back of it as though it would cover something in the very front portion of the differential. Is there a way of adjusting this closer to the dif. should there be such a gap? Could there have been a boot on it before? Please help!