thanks for all the replies. I bought a replacement pinion seal from Rock auto and they said it was for 69' Firebird 350 10-bolt but it seems too big, the pinion shaft barely fits into the rubber of the new seal and really had to force it plus the o.d. seems a bit large (maybe I just need to force that into the axle housing. Any comments, where did you buy yours from ? Are there different sizes for the 10-bolt ????