Tub seal leak caused rusting on transmission but it works, next?

Tub seal leak caused rusting on transmission but it works, next?

Removed tubs to replace the seal. The top of the transmission is rusted badly, however it was working fine before teardown. Can I replace just the cover and the gear bearings to prevent further damage? Any other parts needed? Model 110.82984100 Heavy Duty Kenmore series 80

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