I replaced the one on my 1957 TO35 a few months ago.
I bought the manifold from a local small equipment supplier for around $135.
The new manifold had more flash, than the old one.
I also drilled out the manifold exhaust attachment holes. This way, I could install bolts to attach the exhaust pipe to manifold, rather than screwing the muffler flange to the manifold.
I believe these attachment bolts were originally brass bolts.
You will also need the exhaust pipe gasket and a new manifold to head gasket.
If the head to manifold attachment surface is burned out and not flat, you may have to have the head resurfaced.