Re: Seal wear on shafts
I don't know model numbers and how they relate to years. BUT: if you have a chrysler earlier that 1979 with a two piece lower unit, be absolutely certain that the end float of the propeller shaft is correct at .004-.006. This shaft is carried in a tapered roller bearing. If it has too much end play, the bearin will be too loose, allowing the shaft to wobble in the seal. Under these conditions even a brand new seal on a perfect shaft will leak.
To check your shafts for excessive seal wear, check the wear groove. It should be shallow and polished. You should feel it but your nail should ride over it nicely. say around .002 would be acceptable and a new seal will adequately prevent leaking. If it is rough, or deep enough that your nail would catch in it, it is no good.
bearing supply stores sell generic sleeves that fit over shafts, repairing damage yet using the original part number seals.