I'd do the rebuild, because you never know what you're getting with a used engine, especially given how problematic the N62 engines are.

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2003 X5 4.6 | 2000 540i Touring

Formerly owned:
2004 Range Rover | 2000 M5 | 2000 540i/6
1995 750il | 2003 Mercedes S500 | 2003 540i/6