unfortunately for me here in ohio its winter (early this year).. otherwiser id just go to a Junkyard and grab you one.. from what ive seen most of the thomas conventionals use the same driver belt
this is a place that sells new ones.. I think they ship international? you can call them by telephone (eastern USA timezone) and talk to one of the sales reps if you like..
https://www.tacbusparts.com/Safety/Driver-Seat-Belts
I go there fairly often to buy parts for my busses.. (they are only like 30 min utes from home and a great coffee shop exists down tye street)..
so if they dont ship international i could prob pick one up and ship to you..