So at the Shop we have had alot of the impalas with the 3.5 have head/intake leaking problems. I had mine done under warranty at 52k and another guy...
ya the oil cooler lines are a problem, havent really found a great fix. you can replace with oem or aftermarket and they usually start to leak within...
should be able to add the reindexed keys to level it out as lons as your 3in didnt use reindexed to lift the front already, if it did you could just...