I think you will find your item easier with a item description versus a brand name search. As an example; 12"x2" drum with electric brakes and likely for wheel bolts not wheel studs.
Post a pic.
Used drums may be found at a RV wrecking yard. There are several around the country.
The other comment I have is the repair person should be doing this, not you. They are the expert. Now I realize you are seeking a part for a 53 year old trailer.
1966 Mercury Park Lane 4 DR Breezeway 410 4V, C-6, 2.80 - Streamless.
1966 Lincoln 4 door Convertible 462 4V 1971 Ford LTD Convertible 429 4V Phoenix ~ Yeah it's hot however it's a dry heat!