Mike I didn't mean just the L18..
Here is a partial list of GM engines that use a 2 qt filter.
Make Model Engine
BLUE BIRD+Buses Commercial Bus w/Chevrolet (7.0L) Engine
BLUE BIRD+Buses STC3904 w/Chevrolet (7.0L) Engine
BLUE BIRD+Buses TC1000 w/Chevrolet (7.0L) Engine
BLUE BIRD+Buses TC2000 w/Chevrolet (7.0L) Engine
CHEVROLET/GMC+Buses B6000 w/V8 350 (5.7L) Engine
CHEVROLET/GMC+Buses B6000 w/V8 366 (6.0L) Engine
CHEVROLET/GMC+Buses B6000 w/V8 427 (7.0L) Engine
CHEVROLET/GMC+Buses B7000 w/V8 366 (6.0L) Engine
CHEVROLET/GMC+Buses B7000 w/V8 427 (7.0L) Engine
CHEVROLET/GMC+Trucks (Also Refer To Light Truck Section) 60 Series w/GMC V8 350 (5.7L) Gas Engine
CHEVROLET/GMC+Trucks (Also Refer To Light Truck Section) 60 Series w/GMC V8 366 (6.0L) Gas Engine
CHEVROLET/GMC+Trucks (Also Refer To Light Truck Section) 60 Series w/GMC V8 427 (7.0L) Gas Engine
CHEVROLET/GMC+Trucks (Also Refer To Light Truck Section) 60 Series Lopro w/GMC V8 366 (6.0L) Gas Engine
CHEVROLET/GMC+Trucks (Also Refer To Light Truck Section) 60 Series Lopro w/GMC V8 427 (7.0L) Gas Engine
CHEVROLET/GMC+Trucks (Also Refer To Light Truck Section) 65 Series w/V8 366 (6.0L) Engine
CHEVROLET/GMC+Trucks (Also Refer To Light Truck Section) 65 Series w/V8 366 (6.0L) TBI Engine
CHEVROLET/GMC+Trucks (Also Refer To Light Truck Section) 65 Series w/V8 427 (7.0L) Engine
CHEVROLET/GMC+Trucks (Also Refer To Light Truck Section) 70 Series w/GMC V8 366 (6.0L) Gas Engine
CHEVROLET/GMC+Trucks (Also Refer To Light Truck Section) 70 Series w/GMC V8 427 (7.0L) Gas Engine
CHEVROLET/GMC+Trucks (Also Refer To Light Truck Section) 70 Series w/GMC V8 454 (7.4L) Gas Engine
CHEVROLET/GMC+Trucks (Also Refer To Light Truck Section) 80 Series w/GMC V8 427 (7.0L) Gas Engine
CHEVROLET/GMC+Trucks (Also Refer To Light Truck Section) 80 Series w/V8 427 (7.0L) Engine
CHEVROLET/GMC+Trucks (Also Refer To Light Truck Section) C5000 w/V8 350 (5.7L) Engine
CHEVROLET/GMC+Trucks (Also Refer To Light Truck Section) C5000 w/V8 366 (6.0L) Engine
CHEVROLET/GMC+Trucks (Also Refer To Light Truck Section) C5500 Kodiak w/GMC V8 366 (6.0L) Gas Engine
CHEVROLET/GMC+Trucks (Also Refer To Light Truck Section) C5500 Kodiak w/GMC V8 427 (7.0L) Gas Engine
CHEVROLET/GMC+Trucks (Also Refer To Light Truck Section) C5500 Kodiak w/GMC V8 454 (7.4L) Gas Engine
CHEVROLET/GMC+Trucks (Also Refer To Light Truck Section) C5500 Topkick w/GMC V8 366 (6.0L) Gas Engine
CHEVROLET/GMC+Trucks (Also Refer To Light Truck Section) C5500 Topkick w/GMC V8 427 (7.0L) Gas Engine
CHEVROLET/GMC+Trucks (Also Refer To Light Truck Section) C5500 Topkick w/GMC V8 454 (7.4L) Gas Engine
CHEVROLET/GMC+Trucks (Also Refer To Light Truck Section) C6000 w/6-292 (4.8L) Engine
CHEVROLET/GMC+Trucks (Also Refer To Light Truck Section) C6000 w/V8 350 (5.7L) Engine
CHEVROLET/GMC+Trucks (Also Refer To Light Truck Section) C6000 w/V8 366 (6.0L) Engine
CHEVROLET/GMC+Trucks (Also Refer To Light Truck Section) C6000 w/V8 427 (7.0L) Engine
CHEVROLET/GMC+Trucks (Also Refer To Light Truck Section) C6500 Kodiak w/GMC V8 366 (6.0L) Gas Engine
CHEVROLET/GMC+Trucks (Also Refer To Light Truck Section) C6500 Kodiak w/GMC V8 427 (7.0L) Gas Engine
CHEVROLET/GMC+Trucks (Also Refer To Light Truck Section) C6500 Kodiak w/GMC V8 454 (7.4L) Gas Engine
CHEVROLET/GMC+Trucks (Also Refer To Light Truck Section) C6500 Topkick w/GMC V8 366 (6.0L) Gas Engine
CHEVROLET/GMC+Trucks (Also Refer To Light Truck Section) C6500 Topkick w/GMC V8 427 (7.0L) Gas Engine
CHEVROLET/GMC+Trucks (Also Refer To Light Truck Section) C6500 Topkick w/GMC V8 454 (7.4L) Gas Engine
CHEVROLET/GMC+Trucks (Also Refer To Light Truck Section) C7000 w/V8 366 (6.0L) Engine
CHEVROLET/GMC+Trucks (Also Refer To Light Truck Section) C7000 w/V8 427 (7.0L) Engine
CHEVROLET/GMC+Trucks (Also Refer To Light Truck Section) C7000 w/V8 454 (7.4L) Engine
CHEVROLET/GMC+Trucks (Also Refer To Light Truck Section) C7500 Kodiak w/GMC V8 366 (6.0L) Gas Engine
CHEVROLET/GMC+Trucks (Also Refer To Light Truck Section) C7500 Kodiak w/GMC V8 427 (7.0L) Gas Engine
CHEVROLET/GMC+Trucks (Also Refer To Light Truck Section) C7500 Kodiak w/GMC V8 454 (7.4L) Gas Engine
CHEVROLET/GMC+Trucks (Also Refer To Light Truck Section) C7500 Topkick w/GMC V8 366 (6.0L) Gas Engine
CHEVROLET/GMC+Trucks (Also Refer To Light Truck Section) C7500 Topkick w/GMC V8 427 (7.0L) Gas Engine
CHEVROLET/GMC+Trucks (Also Refer To Light Truck Section) C7500 Topkick w/GMC V8 454 (7.4L) Gas Engine
CHEVROLET/GMC+Trucks (Also Refer To Light Truck Section) C8500 Kodiak w/GMC V8 366 (6.0L) Gas Engine
CHEVROLET/GMC+Trucks (Also Refer To Light Truck Section) C8500 Kodiak w/GMC V8 427 (7.0L) Gas Engine
CHEVROLET/GMC+Trucks (Also Refer To Light Truck Section) C8500 Kodiak w/GMC V8 454 (7.4L) Gas Engine
CHEVROLET/GMC+Trucks (Also Refer To Light Truck Section) C8500 Topkick w/GMC V8 366 (6.0L) Gas Engine
CHEVROLET/GMC+Trucks (Also Refer To Light Truck Section) C8500 Topkick w/GMC V8 427 (7.0L) Gas Engine
CHEVROLET/GMC+Trucks (Also Refer To Light Truck Section) C8500 Topkick w/GMC V8 454 (7.4L) Gas Engine
CHEVROLET/GMC+Trucks (Also Refer To Light Truck Section) Motor Homes w/V8 350 (5.7L) Engine
CHEVROLET/GMC+Trucks (Also Refer To Light Truck Section) Motor Homes w/V8 454 (7.4L) Engine
CHEVROLET/GMC+Trucks (Also Refer To Light Truck Section) T5500 w/GMC V8 366 (6.0L) Gas Engine
CHEVROLET/GMC+Trucks (Also Refer To Light Truck Section) T6 w/V8 366 (6.0L) Engine
CHEVROLET/GMC+Trucks (Also Refer To Light Truck Section) T6500 w/GMC V8 366 (6.0L) Gas Engine
CHEVROLET/GMC+Trucks (Also Refer To Light Truck Section) T6500 w/GMC V8 454 (7.4L) Gas Engine
CHEVROLET/GMC+Trucks (Also Refer To Light Truck Section) T7 w/V8 366 (6.0L) Engine
CHEVROLET/GMC+Trucks (Also Refer To Light Truck Section) T7500 w/GMC V8 366 (6.0L) Gas Engine
CHEVROLET/GMC+Trucks (Also Refer To Light Truck Section) T7500 w/GMC V8 454 (7.4L) Gas Engine
CHEVROLET/GMC+Trucks (Also Refer To Light Truck Section) T8500 w/GMC V8 454 (7.4L) Gas Engine
CHEVROLET/GMC+Trucks (Also Refer To Light Truck Section) W3500 w/GMC V8 350 (5.7L) Gas Engine
CHEVROLET/GMC+Trucks (Also Refer To Light Truck Section) W4500 w/GMC V8 350 (5.7L) Gas Engine
CHEVROLET/GMC+Trucks (Also Refer To Light Truck Section) W6 Series w/GMC V8 350 (5.7L) Gas Engine
CHEVROLET/GMC+Trucks (Also Refer To Light Truck Section) W6 Series w/GMC V8 366 (6.0L) Gas Engine
CHEVROLET/GMC+Trucks (Also Refer To Light Truck Section) W6 Series w/GMC V8 427 (7.0L) Gas Engine
CHEVROLET/GMC+Trucks (Also Refer To Light Truck Section) W6 Series Tiltmaster w/GMC V8 366 (6.0L) Gas Engine
CHEVROLET/GMC+Trucks (Also Refer To Light Truck Section) W7 Series w/GMC V8 350 (5.7L) Gas Engine
CHEVROLET/GMC+Trucks (Also Refer To Light Truck Section) W7 Series w/GMC V8 366 (6.0L) Gas Engine
CHEVROLET/GMC+Trucks (Also Refer To Light Truck Section) W7 Series w/GMC V8 427 (7.0L) Gas Engine
ISUZU+Trucks NPR w/GMC V8 6.0L Gas Engine
ISUZU+Trucks NPR-HD w/GMC V8 6.0L Gas Engine
Why don't they use the PF 454?
OBTW - If you put a 5 in place of the FIL you have the WIX number.. I wonder... naah