The trucks in the pics look like 6-wheel Buckeye trucks with flat bearings, which were commonly used on heavy-duty flat cars, heavy tenders, etc.
I have elevation drawings if you need them (thumbnail, below) but the "Buckeye friction bearing" trucks JohnnyC1 mentioned would probably work. If you need trucks with 36-inch wheels, I believe the 6-wheel Buckeye truck (w/flat bearings) on Ben Neal's 2-6-6-6 tender uses 36" wheels, but the truck does have a brake cylinder attached to it.
In Australia when we transfer locomotives around the workshop while there being worked on they get lifted onto old Steam Tender bogies as the main bogies are being striped and worked on, maybe the photo is the same thing going on.