You bet some of those tubes can be useful! The 5U4 rectifiers, the 6L6 pentodes and the 6SN7 dual-triodes are useful for hifi, among other things. The others, I don't know. Problem in digging through boxes of tubes is when I start seeing, say, RCAs in Sylvania boxes, or box numbering scratched over and relabelled--like someone reboxed questionable/used tubes. If I encountered you at a swap meet, and neither of us could be sure if the tubes were new or used, I might offer $1-2/ea for all of the above. You have (4) 6L6 tubes, and that's good because most buyers will want a quad, preferably all same brand/age.