Riffraff Diesel 6637 Filter Kit

Part Number:



Riffraff Diesel 6637 7.3L Intake Filter Kit

This kit contains: 

- Donaldson 6637 Filter
    - Optional AFe Big Boost washable, or a Donaldson Blue® Filters
- Custom "Riffraff Diesel" Pre-filter Cover (Optional $29)
- Powder Coated Adapter Tube 
    - 94-Early 99 Uses a 45* Mandrel Bent Tube
    - Late 99-03 Uses a straight Tube
- SS T-Bolt Clamp


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  • 4
    works but be prepared

    Posted by Don R on Nov 19th 2020

    it took me awhile to find a way to mount this without the filter rubbing on the master cylinder or reservoir. i had to add an inch of spacers to the donaldson bracket and kept fighting between it rubbing there or rubbing on the hood. the spacer is powder coated well. clamp was nice. i would not let the filter just sit in the engine bay.

  • 4
    6637 Filter Kit

    Posted by Cory on Nov 8th 2020

    I purchased the filter kit thinking that it would be the first of a series of performance upgrades. The kit is nice and includes everything needed to install, but there are a few things to know before starting. First, you will need either to cut your existing airbox to still retain the battery hold down feature while allowing to 6637 filter to fit under the hood without smashing it, or you will need to purchase the $80 Motorcraft battery tray so that you can completely remove the entire factory airbox; this is something that should be explicitly mentioned under the product description. Second, this open element filter makes a lot of noise. It isn’t loud per se, but after driving for even just 30 minutes, my ears are tired of the drone. There are ways to fix this (sound deadening, building an enclosure, etc) but they do add to the cost and complexity of installing a filter. If drone is bothersome to you, or if you want your wife to ride in the truck for extended periods of time, opt for an intake kit that has an enclosure. All in all, it is a great way to gain some additional airflow at a great cost, but it does require either modification or additional parts to complete the install.

  • 5
    6637 filter kit

    Posted by David Compton on Nov 7th 2020

    The 6637 filter kit components are of high quality and fit well in my superduty. Delivery was quick.

  • 5
    6637 kit

    Posted by Bill on Oct 22nd 2020

    Was as descripted, and ift perfectly

  • 5

    Posted by paul on Oct 13th 2020

    i am very pleased with the air filter it works good

  • 5
    6637 kit

    Posted by Joseph Green on Oct 11th 2020

    Easy install great quality. Comes with everything you need. Took maybe 10 minutes to take the old assembly out and install this kit. Sounds great and the retirement is big enough for a Mack truck. Very satisfied

  • 5
    Fits great sounds even better

    Posted by Nick Perry on Oct 8th 2020

    Fits great good quality clamp and pipe and man it makes some beautiful noises.

  • 5

    Posted by Mike K on Oct 6th 2020

    This 6637 Kit with the Donaldson Blue Filter, is the most straight forward, affordable, quality improvement I have installed to date. The results were instantly noticeable the first time I started the truck and headed up our steep dirt driveway. Throttle response is immediate and increased power is phenomenal. Pulling out onto the highway the increased power literally put us back in our seats. Most importantly there is no more lag and the available power makes the truck feel much safer to drive. I stay with Clay because the true value is not just quality and price, but the service before and after the sale. Clay is the most honest, thoughtful, business man I have ever dealt with, providing top quality products, often times within two days, at prices competitive with everyone else in the industry.

  • 5
    Riffraff filter kit

    Posted by TD on Sep 28th 2020

    Great kit, i love the fact they included a new clamp. Installation was pretty easy did not have to do any cutting of the old filter box to get it to fit.