I always replace the pan gasket and filter. There is no more danger in doing this than the old ones.

The fluid is expensive (as you found out). ONLY use the factory fluid.

Don't forget, there is a drain plun in the torque converter too and you will need crush seals for both drain plugs.

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Benzmac:
Donnie Drummonds
ASE CERTIFIED MASTER AUTO TECHNICIAN
MERCEDES SPECIALIST 11 YRS