The engine variants are different. 2007 and 2008 Acadias have an LY7 port-injected engine (VIN code 7). 2009-2016 (plus 2017 Limited) have the LLT direct-injected engine (VIN code D). The swap of variants is probably possible, but it would not be a direct replacement. Electronic controls (ECM/PCM), wiring, fuel system, and a few other items would require significant modification. If you're expecting a direct replacement, look for a 2007-2008 Acadia or Saturn Outlook engine.