[Ron Ramirez]

Goodness, Skip, that was about 300 years ago...

...okay, actually about 42-43 years ago. As I recall I was able to find one at an Evansville wholesale electronics parts distributor. I had to remove one of the new transformer's bells (the one where the wires went through) to retain the original tab mounting to chassis.

Now, your choices are to find a similar RCA with a good power transformer, or pick out something suitable from Hammond. You'll want a horizontal mounting transformer (if you can get one). The RCA service data will help you find a replacement. Suitable RCA donors include 5T, 5T1, 6T, 6K, 6T2, 6T5. Possibly others.

But do test your transformer first as Terry suggested. If it sizzles with no load (all tubes removed), then it has died the death. The power transformer on my RCA 6T2 had lost a lot of tar but it turned out to be OK.