Used to be common triode/pentode output valve used in lots of commercial radiograms and mantel radios. Originally a "low cost amplifier" the audiophiles have hold of them and they sell (well, they ask for) $120 each on eBay on occasion. As a result of these silly prices I do not have many of these, so if you need one ask, as I will be showing zero stock.
The equivalents are CV8297 and ECL86. I may have these too.