* 235 cubic inch inline-six: This was a popular and relatively economical choice.
* 283 cubic inch small-block V8: A more powerful option than the six-cylinder.
* 348 cubic inch big-block V8: This was a larger, more powerful, and less common engine in the half-ton trucks.
So there wasn't *one* size motor. To know for certain what engine a *specific* 1962 C10 had, you'd need to look at its documentation (build sheet, if it still exists) or the vehicle identification number (VIN).