two bolts from underneath, 2 from inside the trunk. super SUPER easy.

I want to say 13 or 14mm

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1992 850i 6 speed
1991 M3 S54B32 swap
2007 328iT/6 RWD sport wagon
1987 325E 330iZHP engine swap
2004 Vespa 200GT
1976 W115 240D getting a much bigger engine. 5.5L
1997 R129 SL600 5AT