Sorry, I misread or misunderstood the question this morning...

Yes, the different size AD truck radiators will all fit, and yes, the difference is the larger trucks have thicker cores.
It makes sense to use a big truck radiator in a small truck for the extra cooling capacity. It would not be a good idea to use a small truck radiator in a big truck.

Grigg

•1951 GMC 250 in the Project Journals
•1948 Chevrolet 6400 - Detroit Diesel 4-53T - Roadranger 10 speed overdrive - 4 wheel disc brakes
•1952 Chevrolet 3800 pickup
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"First, get a clear notion of what you desire to accomplish, and then in all probability you will succeed in doing it..." -Henry Maudslay-