Here are a couple of sources for capacitors.
http://www.tubesandmore.com/
http://www.radiodaze.com/
There are more . . .
It may be tricky to find an exact replacement for a multi-unit can capacitor. Most people either disconnect the old cans and wire new caps under the chassis, or "restuff" the old cans with new caps.
Regards,
Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html