We have lost so much here on the site.
71Spud could have told you everything you need to know about anything to do with this JVC PC series.
The PC-6 has eq AND bass/treble controls, it is the top of the line JVC 3 piece boombox from the late 70s to early 80s, and upgraded version of the PC-3. The PC-5 is actually a 5 piece. The 3 & 5 have just bass and treble knobs, these three boomboxes are as good as it gets.
Youre question seems to indicate that you are basically only interested in flipping boxes. What goodman is politely trying to tell you is that new-in-box these days is probably less valuable than completely %100 mechanically and cosmetically perfect . You are eventually going to have to buy, repair, and sell boomboxes to make any real money on them because simply horse trading has its limits and is time consuming enough to be a black hole of diminishing returns.
imho