There is a company called Harden's musclecar world based in Lexington, MO. They seem to have alot of the odd-ball and hard to find parts for a-bodies. Here's there website http://www.hardensmcw.com/. Good luck finding your parts.
6T9 GTS,
A friend has that same International truck. He built a BIG ole top for it so he can haul 2 horses!
Ever since high school it's been called." The Big I "