104 Rear Main Oil Leak?

[Da Nag]

Just had my head gasket replaced ('95 E320), but after driving for a couple days, there's still an oil leak. Much smaller than before, but it will leave a 1" puddle overnight.

I cleaned things up underneath, and waited for the drip. It appears to be leaking from the engine/transmission junction - it drips from the seam, and I can't find any evidence of oil higher up. It will also continue to drip if the car sits for a couple days. So...rear main seal?

If so, any idea how many hours this should take a competent mechanic to replace?

Thanks,

Bill