I've been building one of the earlier releases of the kit and haven't had any fit issues. The way the cab goes onto the body is a little weird but it fits ok. The front fenders and the floor of the pickup bed are all one unit, with a seperate cab. Most pickups I've built the front fenders are connected to the cab.
I wondered when someone was gonna make mention of the gap between the front fenders and cowling on this one. I seem to recall, from when I was researching a panel delivery for a resin conversion (which I did cast up, BTW, years ago) that there was a fairly large rubber "gasket" or welting that went between fender and cab, and have surmized that this must have been missing on the particular truck that Revell-Monogram referenced in pictures when doing their research on this truck.
Welting was used, and widely so, to provide a dust and water tight seal between separate fenders and the body shell itself on cars and trucks of the "fat fendered" era, and often times is missing on "restored" or rodded vehicles for whatever reason (only the builders know for sure why!). Welting also served to eliminate rattles and squeaks in those areas, given the relative flexibility of sheet metal fenders, along with the often oblong bolt holes in their inner flanges, put there that way for ease of adjustment.
I think, if you research '48 to '52 "Bonus Built" Ford F-series trucks, and find a clear, rear 3/4 shot of one, you will see what I am referring to.
Biscuitbuilder