Warning I know nothing about older jreds.
Found a repo seal, is this it? Jonsereds Crank Seal: 504 14 62-00, 504146200, 504 146200, 504 12 62 00
New reproduction part.
This crankseal fits models: 49sp, 50, 51, 52, 52E, 52 E, 521 E, 521EV, 601, 621, 66e, 70, 70e, 751, 80, 801, 90, 910, 920, 930, 810, 820, 830
http://store.chainsawr.com/products/jonsered-chainsaw-crankshaft-oil-seal-loc-box-x