Can i swap a 3.6 for a 3.8 in my 2005 buick lacrosse?

security system issues between ecm and bcm would be an issue i bet, and you would def need to swap at least all harnesses and ecm and then exhaust and mounts and probably everything may be easier to just swap transaxle also so can match and run together with ecm. and evne then still may not be possible.