Chainsaw Repair

Best method to get correct seals is to measure the hole in the crankcase(o.D.),measure the crank diameter (I.D.),and measure the width of the seal.Go to a bearing supply store,they can get them overnight, but be sure to specify a "Double-lip" seal,or you will likely get a single lip seal- it will have the inside lip but not the outer lip.
Since the seal must hold against pressure and vacuum the 2 lips are more desirable.
And of course they cost much less than factory original...