5U4G suitable for Dyanco ST-70?

When I worked for an electronics store back then, I don't ever remember Dynaco saying it was okay to use them. Here is a copy of the owners manual where on page 9 it states, "A 5U4 type of tube can be used for testing purposes." I have never seen the 5 volt filament ratings that I can remember. A 5U4 draws about 50% more filament current than a 5AR4. They run warm enough with a 5AR4 in them in my opinion. I don't think it's worth the risk, especially if you have a '59 to '62 built unit, with the better transformers a lot of people like.

On page 10 (or 12 of 16 counting the .pdf way)of Hifitime's manual, "The 5U4 or 5U4G can be used in place of the place of the GZ34." Not that everyone here doesn't already know, but the GZ34 is the 5AR4.

Another Dynakit ST70 manual states, "using this tube [5U4G vs 5AR4 - Trelja insertion] type will cut down on the maximum power rating of the amplifier."

As we know, during that era, the goal was to deliver as many watts as possible, and in addition to far better sound, that's what the 5AR4 provides.