I have done this twice. A second set of hands to hold the lower wrench is the issue as the bolt faces upwards (nut on top of the plate). If you use a long ratchet handle it is real easy. Replacement is a challenge as you need to hold 23# of plate up as you install the first one. Hence the second set of arms/hands solution.

I voted to replace both nuts and bolts.

Oil leak will be Alt/Oil filter housing and P/S hoses. God help you if it is the oil pan too.

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2005 X5 4.8IS
The Blue ones are always FASTER....

Current Garage:
2005 X5 4.8is
2002 M5 TiSilver
2003 525iT
1998 528i
Former Garage Stable Highlights
2004 325XiT Sport
1973 De Tomaso Pantera, L Model
1970 Dodge Challenger T/A 4 sp Alpine White
1970 Dodge Challenger T/A 4 sp GoManGo Green
1971 Dart Sport, “Dart Light” package
1969 Road Runner 383
1968 Ply Barracuda 340S FB Sea-foam Green