I am not sure what engines we all have but here is what works for my C8.3 Cummins.
Here are the part numbers I have along with some local costs.
LF3000 (LuberFiner/Fleetguard) ; BD-103 (Baldwin) ; 51748 (Wix) +/- $41 (+/- 22 quarts (15w40 HD diesel oil) with filter change including filling filter with about 2 quarts)
Primary Fuel Filter (w/water separator):
FS1242 (Fleetguard, FS1242B indicates with bowl) ; BF1249 (Baldwin w/o bowl) ; S3201T (Alliance with bowl) +/- $18 - $28
Secondary Fuel Filter:
FF5018 (Fleetguard) ; BF988 (Baldwin) ; 33358 (Wix) +/- $9
WF 2071 (Fleetguard w/4 units DCA, use at each oil change interval, test with strips) ; 24071 (Wix w/4 units DCA) +/- $12
Midland Air Dryer:
DA 33120 +/- $105
DQ 6032 +/- $40
Air Dryer Filter Kit:
DQ 6026 (includes both of the above items) +/- $140
DQ 6020 (includes new purge valve, 1-way check valve, turbo saver valve and all related o-rings etc.) +/- $46
Serpentine Drive Belt:
3926866 (Cummins) ; 5080605 (Dayco), These are for C8.3 engines AFTER 1996.
Engine AC Belt:
The Air filter number I have is from Cummins. It is 0420-HH2 (62891-001) Air Filter (9.75"¯ OD x 24"¯ L).
Our coaches come with Farr ECOLITE Series sealed disposable air filters. The canister and filter is one unit and are disposed of together to minimize dirt being introduced into the intake system. It has a 6"¯ OD connection on one end and the other at the other end, but on the side for our side intake grille.
The unit I have is the #062891001. The Napa/WIX cross reference number is 46891, UPC #765809468917.
Here is one that is a lot cheaper...assuming it is the same.
Their prices are about ½ of what Napa charges in their stores.
FWIW, I would stick with a Farr filter since they are about the best out there in terms of super filtration whereas K&N is among the worst. Additional airflow without an increase in filter medium and size just means that more dirt is getting inside the engine and for diesels, this is VERY BAD.
I also added a Fumoto #F104 drain valve in place of the factory oil pan drain plug to aid in future oil maintenance.
I still have a few items to change/check but hopefully this will help some.