I don't know how hard it is to pull the tranny on a 560SEL because you might have to mess with the exhuast, but I yanked one out of my SDL in just under three hours. With a lift and having done it before its maybe a 4 hour job.

The front seal is very commen, drop the TC and its right their. Yank it out and put a new one in, they cost about $5.

The TC does have a drian plug, and unless its loss it shouldn't be leaking. Rotate the engine around you will find it.

If the trans has other issues, you can get a rebuild for about $1k-$1,200, and just swap it in.

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2016 Corvette Stingray 2LT
1969 280SE
2023 Ram 1500
2007 Tiara 3200