This is my understanding of the radiator options
- All the radiators are about 28 1/4" wide at the core (measure inside the tanks)
- The cores are 17" high and about 21" high radiators
- Depth (front to back) varies from about 1 1/4" to 2 1/2", depending on the number of cores. 2 ancd 3 core are most common, although on a one ton you might find a 4 core. You can remove the cap and look inside to see the number of cores.
When you swap radiators to a different height or depth you usually have to change the top metal bracket, and you always have to change the rubber insert in the frame on the bottom and the bracket on the top. If you have the right rubber insert it will fit right over the radiator end and hold it securely.
I used a Jegs Champion 3 row aluminum radiator for my '75, and it fit fine and works very well. I was replacing a stock 3 row copper radiator, which is probably what you have. However, my truck used the shorter 17" core radiator, while your truck might have the taller 21" core. This aluminum radiator cools much better than my old radiator.
Bruce