BC,
That's kind of a loaded question there. The early 235's, ie 48's, were babbit/low pressure engines. In appearence, you'd never know the difference between one of these, and a 216.
Now when you get into the later 235's, the valve cover's are different, held on by 4 bolts into the head, rather than the two acorn nuts on top. Also, the side covers are different.
On the early 216/235's, the side cover was tall, and went up and around the spark plugs. The later 235's it was a short cover that stopped well below the plugs.
With all of that said, a 48 - 1/2-ton would have normally come with a 216, as the 235's were made for the larger trucks.
I have a 48 - 235 in my 52 1/2-ton, good motor.
Hope that helps.
