Unfortunately, that data would likely be buried in a Toyota Powertrain engineer's archived worksheets in a warehouse in Japan and the electronic version offline and similarly archived somewhere on storage media. Said engineer may now be an HVAC engineer working on the next generation of medium duty trucks, or have been transferred to Scion, etc.
Just wanted to give a little flavor of how it would be nigh impossible to ask someone at Toyota to track an obscure figure like that on a vehicle designed 18 years ago. When I worked there, the stuff for the current model year, and the year before were kept on hand, and the rest somewhere in archives.
In regards to the original question, if you're considering finding a used radiator, I'd reconsider. A junkyard will charge you at least a couple hundred, and a new one is only a couple hundred more. By the time you pull the old one and install the - well, the old one again you might wish that for all the trouble your truck didn't have a radiator that could start leaking at any time. The downside of putting a used rad in is that this component can cost you huge $$$ if it fails by damaging lots of other stuff.
Plus, if you buy the new Toyota unit, you get to choose the far superior 93/94 version.......heh...