A used control unit is not a spare part in the way a wing is. On a G60 almost everything hangs off coded modules, and a unit out of another car carries that car's chassis number and equipment list with it. Before it will work it has to be written to the new vehicle — on some modules that is routine, on others the manufacturer's protection stops you.
Which makes part numbers matter more here than usual. The G60 arrived in 2023 and is built as a combustion car, a plug-in hybrid and an i5 on one body, and the control units differ between those versions even where the casing looks identical.
Gearboxes follow a different rule. The eight-speed automatic is mechanically tough and usually outlives the car around it. What it does not outlive is a driveline impact — which is exactly how the good used examples reach the market.
