I am new at this but would like to add. Racor does make a replacement filter for oem that has a different ellement or this is what I am told by Racor Rep. It has the same 2 mic rateing that is in the 660 people are adding and for that fact is supposed to be the same ellement. It has a totaly different part#. And one is on its way here been tracking and is 1/2 way. It was quoted to me " the one that is OEM is of GM,s specs this is of Racor specs even though we build the filter for GM there is a big difference " The filter will be here tommarow so Ill post what I find after I see it. Well we will see and I still believe a second is a must. David