As already explained, and is my opinion too, that if used regularly as a real 1 ton truck the transmission from a 1/4 ton truck may not last.
I understand they’re not weak, and in high HP, but light, cars they do well.
A car is not a truck though.
If they were a suitable transmission for a larger truck I believe GM would have saved themselves some money and used the T5 in bigger trucks. They didn’t, probably because they didn’t think they would last long enough.
The 5 speed overdrive from a 3/4 or 1 ton that is a reasonable swap is the NV4500.
Just my opinion
