Flushing is easier, you don't even have to jack it up or crawl under. As has been said do it at the rad, just don't do what i did when I disconnected the return line by mistake. What a mess on the garage floor till I got er shut down.

There is only one transmission mount and it's easy to change. They normally do not fail unless leaked upon by oil or tranny juice.

I would leave the rear transmission seal and bushing alone unless it is loose or leaking.
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David Hunter