The way i figured this swap is rwd only conversion, whatever trans best fits and can handle the power.

Get a built rear diff, and really what else is there thats going to break? Custom driveshaft if needed and they arent too expensive as well..

I may make it sound to easy 4.6 motor may be easier to work with then a 4.8, however at a certain point in time to do a full top to bottom gasket, cooling system things, valvetronic/vanos crap etc, and even get the ess supercharger really aint cheap either... And it still wont be at 500whp after all of that.

Versus doing the LS swap, procharger or whatever else is a good add-on for the LS's, will be more reliable, more power and you can drive the car another 150-200k.

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2006 X5 4.8is Fully Loaded