Is the 3 watt Hammond my only choice, Cap'n? The 50c5 doesn't crank out any nore, huh? I guess I was hoping the "Sears Model 5XL" might mean 5 watts. What a gullible victim of marketing I am.
This photo shows how CE Blue and I mounted the new N-51X Iso Tranny. It also shows the output transformer mounted on the speaker frame. It seems to be working but it sure looks gnarly. The idea would be to replace the speaker and mount the new OT on the opposite side of the box as the Iso Tranny. There is definitely no room on the inside on the shelf with the other components.
PS - I have no fuse, either.
PSS - I just answered my own question by finding the spec sheet on the 50C5. Max output = 2.3 watts.