This one has five valves, but as someone who cut their teeth on 5-valve B&S F tubas, it's like returning home after a long time. I sold my old 5v B&S JBL Classics F almost 11 years ago.
There's been a bit of work done on this one. The fifth valve has been converted to right hand thumb using Miraphone parts, but it's a really nicely-done conversion so I can't complain about that. (Original LH thumb parts are included if I ever want to convert it back to stock.) The leadpipe was also replaced along with the bottom bow guard. Linkages and paddles have been replaced with modern B&S paddles and 3B links, which is a nice touch, and they're silent. Not a perfect cosmetic instrument, but a really fine player, and definitely something I would like to hang on to long-term.
With the fifth circuit pulled almost to the limit, I can just barely get a flat-enough low Bb, so I would definitely like to extend that a bit. I'd also like to vent the valves. Otherwise, it's pretty much good to go.
Bad pic in the living room with all the kid stuff around:

