Go to an engineering workshop with a mandrel complete with blade & pulley
Also a photo of it mounted into the deck and ask him yo make you one in steel pipe.
We had / have a company in South Australia that has been selling them on ebay for a while .
You could try looking on ebay.com.au but with freight rates it should be a lot cheaper to get them made locally
Just 2 pieces of pipe welded into each other to locate the bearings then a flange welded to the bigger one to mount it plus a few webs to support the flange and help locate on the deck.
Now the danger with this is if you are smacking into solid things like tree roots, fence pickets, rocks etc then once you replace the weakest link, something else will give way
So you will either bend the deck or the blades or both .
Down here we fit a swing back blade holder when we go to the steel mandrel
like this
Just fitting the adapter & using swing backs has overcome the broken housing problems for some of my customers.
Cox used to export to Canada so you might be able to get the blades from there.
The USA banned swing back blades in the 80's for use on domestic mowers
You might even be able to get an adapter made to take the JD swing back finish mower blades used on tow behinds on real tractors.