In my opinion you get what you pay for when it comes to fiberglass parts.
I have some 40 rear fenders and one fit OK but the other was twisted because it was probably not cured long enough before removing from the form. I read that is how some are cheaper is because they only have one form so the sooner they are removed the sooner they can make more. Thus the more quantity the cheaper the price.
As far as original Car versus Truck, the lip that bolts to the cowl is flat on the truck and angled on the car. I think the contour is the same so you probably could with a little work make them fit.
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Dan
01 Mustang(wife's car)
95 Mustang
81 F100 Custom Explorer
63 Falcon
59 F100 Flareside (wife's truck)
40 Ford pickup
39 Ford pickup
Mitch, check out this web site, this guy seems to have used fenders for 40s trucks that look pretty good. J.T.'s Antique Trucks and Vehicles go to the bottom of the list and click on the parts section Where in Indiana do you live?