I have one of these. One of these days I'll post some pictures of the interior. It's pretty well packed in there. Sony may have built it, but they used Tek parts.
I just bought a spare for parts, but the packaging was marginal and the post office used it as a football (note: do NOT mark your package as fragile! The temptation to abuse it is irresistible!

). The CRT is a directly heated cathode and is fairly fragile. This scope suffered a severe G shock and distorted some of the internal geometry, so the CRT is useless.
Pretty cool scope though - 35MHz dual channel with delayed sweep and will run off of line or 12V, 1mv/div sensitivity. The attenuator for both channels uses a coaxial control. It's a little funky, but they were running out of real estate on the front panel.
Sony/Tek also made the 308, a cute little 8 bit logic analyzer along with some other scopes. I think the 335 was the highest bandwidth model.