rear main bearing seal fused in place

[alderan33]

I have the engine out of my 72 C10. It's a 350. I am freshening it up with a timing chain and oil pump, seals, freeze plugs, etc.. I am trying to change the rear main bearing seal. I removed the cap and after several minutes of gentle prying was able to remove upper piece. It was REALLY on there. The lower piece, however, seems to be securely fused in place. I have tapped it carefully but it will not move. I don't want to further degrade its structural integrity by bludgeoning it. I believe this is the original motor so it has been in place since the factory. Am I going to have to remove the crank to replace the lower part of the seal? I don't have the money for another motor or even a longblock. Any ideas would be most appreciated.