Only if the original 9N PTO was replaced or upgraded. The early machines had a "funky" seal assembly. Check out this web page for information:
My suggestion if you still have the old PTO style shaft is to replace the whole thing. It will come with an 1-3/8" PTO and a normal lip-style seal. If your trying to keep the outside of the tractor looking original, I hear that you can switch out the new steel bearing retainer with your old cast iron one. Not sure if any modifications are needed though.