Packard steamer update

Brett Ventura Writes:
The coils are rotted from the inside, Visited Tom Kimmel last month, (what a collection!) he is currently winding new coils and I am making a new coil shell & combustion chamber.
The I disassembled the differential yesterday, I think the guy welded the original Packard axle tube onto the Stanley. All the bearings need replaced, the threads on the end of the one shaft are stripped, and the taper was not cut right for the drums & required a shim (the axle with the shim had the stripped threads, would have lost a wheel). He also made a wheel spacer to widen the stance. I have decided to do away with all of this, and go to a modern drum setup from a Chevy truck. I would have to cut the old tubes off, and start over fresh. Does anyone know if the axle & housing are cast iron or cast steel? I can do the drill or spark test but figured I would ask here first. Open to any other ideas.
Also, the center of the spider/spur gear has some wear, just make a bushing I’m guessing?
What did the Stanley axle have originally to hold the wheel on? Was it a taper or just a key? I have not seen one apart.