Tim, it's hard to tell what you meant in your response. By "1.2 ton trucks" did you mean to say "1/2 ton trucks" or "1(to)2 ton trucks?"
I'm pretty sure the '48's were three-on-the-tree. Mine is, as are all the other '48 half tons I've seen. The '47's were floor shifts, and they went to the column shift in '48.