The guy I go the truck said it was just changed to a K&N, so I let it go. Today 9 months later, I pull it out and its in such bad shape. There is so much road grime and grease like crap in there with a few nuts from the trees I guess. Well, Im going to get a paper filter this time, Ive heard bad things about the K&N. What is the sensor in the box? That thing was completely covered! Also The box has a broken tap, fortunatly there is nothing on the other side of the filter. Now I have a early 99, so what are my options? Can I get the newer filter box as a direct bolt in?

 

that is the "intake air temp sensor" just clean it off with some carb cleaner

 

Try the 6637 NAPA filter. I got the idea from Kwik and I like it, a little more throttle response.

 

190,000 on my K&N and never a single problem.

 

I had a problem with a K&N and a early 99 also. Part of the problem is that the stock airbox pulls air off the driver's side front wheel well. I can remember changing paper filters every time i pulled my trailer when it was raining. I then switched to a K&N. Some where in the process of driving 130k miles, some of the tabs broke off and the top of the airbox was only held on by one plastic tab and the two metal retainers. At about 125K miles i took the truck into Ford to have them replace a couple of injectors and they discovered the broken airbox and decided to check the compressor blades on the turbo. Apparently crap had gotten past the filter and did some damage on the turbo. I had them replace the old airbox with one of the Ford AIS airboxes (direct bolt in). It cost me almost $ 300 but i am very satisified. If you don't like your airbox, you might try an AIS airbox or later model airbox. OR, you could try a cold air intake airbox.

I like the AIS airbox because of the increased filtering capacity and quality and it sucks air from near the radiator like in the 99.5 and later 7.3L diesels.

 

Here's the link to the 6637 Napa filter mod:https://www.ford-trucks.com/forums/s...d.php?t=277571

 

Also consider Tymar it is paper element open filter that replacs OEM box completely $109.
Kwik has a home made version that also works well, so I hear.

 

I just returned from a dyno pull, personally met Quadzilla and some other guys with some awsome trucks and just about all of them had the 6637 installed.

 

Kwikk I just looked at the NAPA 6637 filter at the link you posted above. It looks very much like the Donaldson used by Tymar. How does it compare in use? Will it replace the Donaldson without having to modify the flange?

 

I have no idea on the comparison or replacement. For my own experience I have had the same one in there now for about 5000 miles and it's getting a little grey. I'll be replacing it before the vacation season hits, but I know it will not be required, I just want a new filter for the long drives. Saturday I was on the way down to the dyno pulls and blew a clamp on the Y-pipe. I had to take the Y-pipe off and degrease everything to make sure that it would stay on there. I peered down the intake manifold and was glad to see the absolute lack of any dust, dirt, any type of residue whatsoever.

 

The NAPA and Donaldson filters are basically the same, just different vendors. I use the Luberfiner version of the same filter. It is the same as the Donaldson and came with a sticker on the element showing it had the same Microlite* paper. I feel it is just as good as the Donaldson. I get mine from my diesel truck part supplier at the company I work for.

 

Sounds reasonable to me.
Now its a matter of price and availability