Frame Differences

[ssapach]

I did a little searching for other threads on the topic, but I wasn't finding the answers to the question I have.

I have access to a 1981 GMC 3/4 ton 4x4 that is in relatively good shape for it's age and location. The rear end is a 14-bolt SF axle but the truck has 8-lug hubs all around.

Would this be a plain old 3/4 ton frame or is there a "light duty" 3/4 ton and a "heavy duty" 3/4 ton truck of this style?

My understanding is that there are differences in the material thicknesses between 1/2, 3/4 or 1 ton frames. I could also do a bit of measuring on it to find out for sure, but I don't actually know the differences between the frames.