I believe Toyota even made a 1 ton usually. Best examples are the Uhaul box vans and the tiny motorhomes.
I almost had a motor home for $750. It was running and all. Had a leak on the roof e to new ad install but it was still a steal with new carpet and stuff. Think they get 25mpg or better on the 4 cyl.
Drove a 1981 Datsun diesel back in the day, very similar to that Toyota. It was rated as a 3/4 ton I think. A lot of low end torque but would only do 70 mph down hill on a good day!
By the way ......what intercooler? J/K