Magnum was Safari's chassis subsidiary and it was absorbed into Monaco's Roadmaster division when they bought Safari. But the axles and hubs came from a supplier, you you have to figure out what brand of axle and wheel you have. Arvin-Meritor, maybe? I would think any medium/heavy duty truck shop or parts house could identify the brand if they could get a look at it. Or just take the parts into a NAPA store and they can probably find one to match.
2004 American Tradition; 2014 Buick LaCRosse
Homebase in the Ocala Nat'l Forest near Ocala, FL