name that tube

>>No, but 5V4s and 5Y3s are basically interchangable<<

No, they are not.

For example, 5Y3 is a popular rectifier for 2A3 amps and 5V4 for 45 amps.

Now, using your assertion, stick that 5Y3 into the 45 amp and watch the snap, crackle, pop action of your triodes.

Very bad information.

Sorry, Darosenb my post is in error. The idea was correct but the typing was not.

An amplifier manufacturer I represent vigorously cautions against using the 5V4 with a 45 as you point out.

The 5Y3 is appropriate for the 45 Triode and could work with the 2A3 in many circumstances.

My bad.

Don't try this at home.