FLSL55

I found two part numbers for our cars online. 33-2859 and 33-2181.

They both have different dimensions. I think 33-2859 is discontinued but places like Amazon still show them in stock.

What part number is the best "fit" for our cars?

I found a place online that sells the 33-2181 for $29.99 with free shipping and a $5 processing fee. I misplaced the bookmark. They never responded back to my email. I am hesitant doing business with a company with bad customer service.

FLSL55

What K&N part number do you have in your SL55?

sjcsl55

I have the 33-2181... appear to fit perfectly. Bought mine via amazon.com, no tax free shipping..

LOVEMYBS

Go to the K&N website. Follow the prompts for your car and it will tell you what filter to use. I believe the 2181 was replaced by the 2859 or vice versa; I can't remember. In any event they are the same filter with the same dimensions. K&N made the change for inventory control purposes. I went through this exercise several months ago and purchased whatever they recommended. So far no problems.

BeltFedBob

I have a set of 33-2181's in my office waiting for the day...
These fit the 05 SL55 and remember they take two.

lauer87

Got mine from Advanced Auto Part