Half Ton Pickup Rear Fender Shape Change

[southfork]

I was wondering when the sloping rear fenders typical of the '40/'41 Ford 1/2 ton pickups became boxy. Was it on the 1948 F1 Pickups? or was it before that? I drug home a home made trailer the other day that uses a Ford pickup bed (49" wide and 79" long), and it has the beautiful sloping rear fenders. What years had them? I need to know so I can locate a correct tailgate for the bed.

 

[46truck]

40/41 @ 42/7 Ford truckrear fenders are similar, but will not interchange. The 48 truck was the first to use the "box" type fender

 

[georgewarren]

I and hamtownal have mixed/matched 38 thru 47 rear fenders with no apparent problems.