You don't need to clamp the fan, just hold it. I use a regular 8mm allen wrench, but on the W126 their is more room. You may either have to cut the wrench down or pull the radiator. The W124 is tight.

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