Hi, I need to install on a 09 yukon ( GMT 900 platform) a retrofit interior cabin air filters ( are two on late models year) , because the last model year comes with them was 2002. Anybody has made the work ? or know any filters useful for this proposal ? is very difficult to replace the evaporator cases lower and upper ? I am thinking to purchase a new cases ( are cheap) and work externally on them installing the filters .Thanks in advance.