Replace the output shaft seal while it is out and replace the rear main seal in the engine if it is a normal lip seal. If the rear main seal in this engine is like the diesels then leave it alone.

You are going to want to remove the rear transmission mount to let the rear of it hang down as far as it can. With this done use a really long extension to get a socket on the upper most fasteners that hold the transmission to the engine. Do you have a jack for the transmission?

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Jim