the numbers for 405,504,505,604 K&N Filters are as follows:
504
1971-78 2L #E-2360
504D
1980-81 2.3L #E-2300
505D
1980-81 2.3L #E-2300
604
1979-80 2.5L(?) #E-3740
405
1987 1.4L #E-9121
1988 1.6&1.9 #33-2539
1992 1.8L #33-2673
This is from last years catalog. Hope this helps
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Chris Youngson, VE7CST
West Vancouver
British Columbia
Canada
Member: L'Adventure Peugeot
1981 Peugeot 504TD Wagon
1979 Peugeot 504D Sedan
1978 Peugeot 504D Wagon
1965 Land-Rover 109 Petrol 3-Door
1988 Chrysler Daytona