I don't know about internationals specifically, but it was common for medium duty trucks to have a build sticker with all the optional part numbers listed. You'd look there to see the axle type or brake parts. This is not the kind of thing you'll find easily listed online, maybe you'll find the numbers looking around on International sites, or maybe you'll have to call or email some places that deal in old parts. Not saying the new parts places can't find it, but you won't find it listed on their site, and the kid at the counter probably can't help you, you'll need to find "the guy".
Or you can risk it and take it out then match up what you find. I'd be 99% sure you could get one reasonably without haveing to have the old one relined.