[ETO_Alpha] Converting a 76A to 3CX800A7's Question

[Robert Dorchuck W6VY]

I have a question about converting a 76A to use 3CX800A7's.  What does one
  use for a filament transformer?  I see that some are mounted under the tube
  deck but I cannot find any 12.6 volt transformer rated at 3 amps that will fit.
   
  Thanks,
  Bob  W6VY