Upload & Sell: On
The Vivitar Series 1 "solid cats" have an excellent reputation; 400mm f/4.5, 600mm f/8, and 800mm f/11. I owned the 600/8 and it had very nice IQ, except for the donuts, which I prefer with coffee, not in images. Otherwise, I'd still have it. The Vivitar Series 1 400/4.5 has the best reputation, but it is rare and the most expensive. The solid cats are just that, solid, with no air gaps. This makes them far less susceptible to misalignment problems than other cats, which are prone to misalignment after one or a few moderate 'knocks'. The solid cats were designed by Perkin-Elmer, who also brought us the Hubble Space Telescope.
The Tamron SP 350/5.6 Cat also has a very good rep, and it's quite small and light. Of course, it's also hard to come by, and relatively expensive, and so I haven't yet managed to snag one.
The four cats mentioned above are tracked in Lens$db; the Vivitar are at the bottom of the LNOP page, and the SP is with the other Tamron lenses.